Solid random elastomeric copolymers

ABSTRACT

There is disclosed a linear block copolymer comprising at least one triblock I-B-I, wherein I is a block of a polymerized conjugated diene of at least 5 carbon atoms, such as isoprene, and B is a block of a polymer of a conjugated diene, different from that of formula (1), of at least 4 carbon atoms, such as 1,3-butadiene. The B block is selectively hydrogenated, while each of the I blocks retains a sufficient amount of its original unsaturation to vulcanize the copolymer. There is also disclosed an alternative linear block copolymer containing at least one triblock of the first polymer block made from an aryl-substituted olefin, such as styrene, and the conjugated diene used to polymerize the block I, the second middle polymer block of the diene used to polymerize the block B, and the third polymer block which is the same as the first polymer block. In this alternative copolymer, the middle block is also selectively hydrogenated, thereby leaving the terminal polymer blocks with a sufficient amount of double bonds to vulcanize the copolymer. The polymers can be crosslinked or functionalized through the terminal blocks containing the vinyl unsaturation. There are also disclosed random and star-branched block and random copolymers made from the same monomers as the linear block copolymers. Also disclosed are methods of producing and selectively hydrogenating the polymers.

This application is a divisional of application Ser. No. 08/029,507,filed Mar. 11, 1993, now U.S. Pat. No. 5,306,780, which is a divisionalof Ser. No. 07/952,127, filed Sep. 25, 1992, now U.S. Pat. No.5,268,427, which is a divisional of application Ser. No. 07/466,233,filed Jan. 16, 1990 and now U.S. Pat. No. 5,187,236.

This application is also related by subject matter to application Ser.No. 07/466,135, filed Jan. 16, 1990, now U.S. Pat. No. 5,149,895 and toapplication Ser. No. 07/466,136, filed Jan. 16, 1990.

The entire contents of application Ser. No. 07/466,136 are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to novel elastomeric block copolymers havingunsaturation only on the terminal blocks and methods of preparationthereof. More particularly, the invention is directed to solidelastomeric block copolymers comprising triblock units wherein themiddle block of each triblock unit is substantially selectivelyhydrogenated and therefore contains substantially no unsaturated groups,while each of the terminal blocks of each triblock unit contains asufficient amount of unsaturation for curing the block copolymers.

The invention is also directed to random copolymers which, whenselectively hydrogenated, contain elastomeric molecules havingsubstantially saturated backbones and random, pendant unsaturation.

The invention is additionally directed to chemically modifiedderivatives of the above block and random copolymers.

Crosslinking of the polymers of the invention produces vulcanizateshaving unusual properties, e.g., high elongation and excellent agingcharacteristics.

2. Description of Related Art

Elastomers (or rubbers) of either natural or synthetic origin usuallyrequire vulcanization for transformation into insoluble, non-deformablehigh strength elastomeric products. Before vulcanization, rubberspossess inferior properties and low strength which limit their utility.

There are a number of well known methods for achieving thevulcanization, also referred to as crosslinking, of unsaturatedelastomers. Such methods include the use of sulfur and accelerators,peroxides, benzoquinone dioxime, certain phenolic resins and similaragents. Any of the above or any other well known vulcanizing techniquesmay be utilized to crosslink the elastomers of this invention.

The great majority of currently known synthetic elastomers are based onpolymers or copolymers of butadiene or isoprene. These polymers, whichinclude cis-polybutadiene, emulsion polybutadiene (EBR),styrene-butadiene copolmer (SBR), butadiene-acrylonitrile copolymer(NBR) and cis-polyisoprene, provide raw materials for the production ofa very large volume of rubber goods, such as automotive tires, conveyorbelts, adhesives, footwear, sponge and mechanical goods. Because of thehigh degree of unsaturation inherent in the polymeric backbones, theseelastomers are easily and quickly vulcanizable alone or in blends. Asecondary consequence of the high degree of backbone unsaturation is theinstability of such elastomers in the presence of ozone and oxygen, bothof which promote rapid deterioration of these elastomers.

Butyl rubber, which is a copolymer of isobutylene and 2-3% by weight(wt.) of isoprene, represents a class of elastomers far more resistantto oxygen and ozone than those based on butadiene or isoprene. Thebackbone of butyl rubber is primarily polyisobutylene (which provides asaturated spine) into which there is randomly copolymerized about 2-3%by wt. of isoprene to provide unsaturated sites for vulcanization. Butylrubber finds limited use because of its relatively poor elastomerproperties, and is used primarily in applications which take advantageof its damping properties, weathering resistance and low gaspermeability.

Ethylene-propylene-diene rubber (EPDM) has enjoyed substantialcommercial growth as a synthetic rubber since it combines excellentoxidation resistance with good elastomeric properties. This elastomer isprepared by the polymerization of ethylene, propylene and anon-conjugated diene, such as 1,4-hexadiene, dicyclopentadiene orethylidene norbornene. Diene incorporation is typically 5-10% by weight(wt.). The diene is randomly incorporated into the saturatedethylene-propylene backbone to provide pendant vulcanization sites.

The above prior art elastomers, with either high or low levels ofunsaturation, are characterized in that, having random unsaturation,they are randomly crosslinked during vulcanization. The success ofvulcanization in incorporating all molecular chains into the finalcrosslinked network with minimal "loose ends" is termed the degree ofnetwork perfection. An imperfect network, wherein crosslinks occurrandomly and sometimes not near the end of a molecular chain, produces avulcanized polymer having poor mechanical and elastomeric propertiescaused by chain ends which are not a part of the tightly bound network.In order to insure the highest degree of network perfection attainable,randomly unsaturated elastomers must be crosslinked extensively. Thelarge number of crosslinks necessary (25 to 40 per 100,000 molecularweight) dictates that the average distance between crosslinks (M_(c))must be relatively small in comparison with the dimensions of the wholemolecule. Elastomeric properties, such as elongation, depend greatly onM_(c) --the smaller the M_(c) the worse are the elastomeric properties,e.g., the lower the elongation of the vulcanized polymer.

Various block copolymers having excellent elastomeric properties,especially elongation, have been made in the past. For example, a blockcopolymer commonly known as KRATON, manufactured by Shell ChemicalCompany, which has outstanding properties at room temperature, is athermoplastic elastomer consisting of block segments of polymerizedstyrene units and polymerized aliphatic diolefin units, such asbutadiene or isoprene. The most common structure of KRATON is the linearA--D--A block, such as styrene-butadiene-styrene (S--B--S) orstyrene-isoprene-styrene (S--I--S). One of such rubbers is believed tobe described by Jones, U.S. Pat. No. 3,431,323. Jones discloses blockcopolymers containing block segments of polymerized vinyl arene monomerunits, e.g., styrene, butadiene monomer units, and vinyl arene units.After the block copolymer is prepared, it may be subjected tohydrogenation to such a degree that the unsaturation of thepolybutadiene block is reduced to less than 10% of its original value,while 10-25% of the poly-vinyl arene block segments are hydrogenated.Although the KRATON triblock copolymers have excellent elastomericproperties at room temperature, since they are thermoplastic materialsthey lose these properties at temperatures of about 80° C. (and higher).In addition, since these polymers are not chemically crosslinked, theyare soluble in many organic solvents. These latter two deficienciesplace some restrictions on the viable areas of application for thesepolymers.

Falk, JOURNAL OF POLYMER SCIENCE: PART A-1, Volume 9, 2617-2623 (1971),the entire contents of which are incorporated herein by reference,discloses a method of selectively hydrogenating 1,4-polybutadiene unitsin the presence of 1,4-polyisoprene units. More particularly, Falkdiscloses selective hydrogenation of the 1,4-polybutadiene block segmentin the block copolymer of1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene and in randomcopolymers of butadiene and isoprene, with both polymerized monomershaving predominately 1,4-microstructure. Selective hydrogenation isconducted in the presence of hydrogen and a catalyst made by thereaction of organoaluminum or lithium compounds with transition metalsalts of 2-ethylhexanoic acid.

Falk, DIE ANGEWANDTE CHEMIE 21 (1972) 17-23 (No. 286), the entirecontents of which are also incorporated herein by reference, disclosesthe selective hydrogenation of 1,4-polybutadiene segments in a blockcopolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene.

Hoxmeier, Published European Patent Application 88202449.0, filed onNov. 2, 1988, Publication Number 0 315 280, published on May 10, 1989,discloses a method of selectively hydrogenating a polymer made from atleast two different conjugated diolefins. One of the two diolefins ismore substituted in the 2,3 and/or 4 carbon atoms than the otherdiolefin and produces tri-or tetra-substituted double bond afterpolymerization. The selective hydrogenation is conducted under suchconditions as to hydrogenate the ethylenic unsaturation incorporatedinto the polymer from the lesser substituted conjugated diolefin, whileleaving unsaturated at least a portion of the tri- or tetra- ethylenicunsaturation incorporated into the polymer by the more substitutedconjugated diolefin.

Mohajer et al., Hydrogenated linear block copolymers of butadiene andisoprene: effects of variation of composition and sequence architectureon properties, 23 POLYMER 1523-1535 (Sep. 1982) disclose essentiallycompletely hydrogenated butadiene-isoprene-butadiene (HBIB), HIBI andHBI block copolymers in which butadiene has predominantly1,4-microstructure.

Kuraray K K, Japanese published patent application No. JP-328729, filedon Dec. 12, 1987, published on Jul. 4, 1989, discloses a resincomposition comprising 70-99% wt. of a polyolefin (preferablypolyethylene or polypropylene) and 1-30% wt. of a copolymer obtained byhydrogenation of at least 50% of unsaturated bond of isoprene/butadienecopolymer.

Heretofore, the art has failed to produce a polymer having a saturatedbackbone for oxidation stability which has unsaturated bonds only on theends of the block polymer chain. Such a block polymer could bevulcanized or selectively functionalized at the terminal ends thereof.The functionalization would expand the utility of the polymer.

SUMMARY OF THE INVENTION

In one embodiment of the invention, there is provided a high molecularweight, solid block copolymer comprising at least three alternatingblocks:

    (I).sub.x --(B).sub.y --(I).sub.x

wherein I is a block of at least one polymerized conjugated diene havingat least five (5) carbon atoms and the following formula ##STR1##wherein R¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided thatat least one of R¹ -R⁶ is a hydrocarbyl group and further provided thatthe structure of the residual double bond in the polymerized block I hasthe following formula ##STR2## wherein R^(I), R^(II), R^(III) and R^(IV)are each hydrogen or a hydrocarbyl group, provided that either bothR^(I) and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups; B is a block of a polymer of at least one conjugateddiene, different from that used to polymerize the I block, having atleast four (4) carbon atoms and the following formula ##STR3## whereinR⁷ -R¹² are each hydrogen or a hydrocarbyl group, provided that thestructure of the residual double bond in the polymerized conjugateddiene of formula (3) (block B) has the following formula ##STR4##wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(a) or R^(b) is hydrogen, oneof R^(c) or R^(d) is hydrogen and at least one of R^(a), R^(b), R^(c) orR^(d) is a hydrocarbyl group; x is 1-100, preferably 2-100, mostpreferably 2-30and y is 300-35,000, preferably 1,000-5,000, and mostpreferably 1,500-4,000. It will be apparent to those skilled in the artthat in the residual double bond of formula (2) R', R", R'" and R^(IV)may all be hydrocarbyl groups. The hydrocarbyl group or groups in theformulae (1) and (2) are the same or different and they are substitutedor unsubstituted alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkarylor aralkyl groups or any isomers thereof. Examples of suitableconjugated dienes used to polymerize the I block are isoprene,2,3-dimethyl butadiene, 2 -methyl-1,3-pentadiene or myrcene. Thehydrocarbyl groups in formulae (3) and (4) are the same as thosedescribed above in conjunction with the discussion of formulae (1) and(2). Suitable conjugated dienes used to polymerize the B block are1,3-butadiene or 1,3-pentadiene. After the polymerization is completed,the block polymer is hydrogenated, so that the B block is selectivelyhydrogenated to such an extent that it contains substantially none ofthe original unsaturation, while each of the blocks I retains asufficient amount of its original unsaturation to cure (or vulcanize)the block copolymer. The block copolymer is terminated at both ends witha block I.

In an alternative embodiment, there is provided a block copolymercomprising at least three alternating blocks:

    (A).sub.x --(D).sub.y --(A).sub.x

wherein the A block is a random or block copolymer of at least onearyl-substituted olefin, such as styrene, 2-phenyl alpha-olefins,alkylated styrene, vinyl naphthalene or alkylated vinyl naphthalene, andat least one conjugated diene of formula (1), discussed above, such asisoprene, 2,3-dimethyl butadiene, 2-methyl-1,3-pentadiene or myrcene;and D is a block of a polymer of at least one conjugated diene offormula (3), discussed above, which is different from the conjugateddiene of formula (1), e.g., 1,3-butadiene or 1,3-pentadiene. When theblock A has molecular weight of about 350 to about 7,500, it comprisesabout 50 to about 65%, preferably about 50% by mole of thearyl-substituted olefin, and about 35% to about 50%, preferably about50% by mole of the conjugated diene of formula (1). When the block A hasmolecular weight of about 7,500 to about 20,000, it comprises about 1 toabout 99%, preferably about 80 to about 98% by mole of thearyl-substituted olefin, and about 99 to about 1%, preferably about 2 toabout 20% by mole of the conjugated diene of formula (1). When the blockA has molecular weight of about 350 to about 7,500, x represents thetotal number of monomer units in the block A, such that the blockcopolymer comprises about 0.25 to about 10%, preferably about 2 to about10% wt. of the A blocks, and y represents the total number of monomerunits in the block D, such that the block copolymer comprises about 80to about 99.5%, preferably about 80 to about 96% wt. of the D blocks.When the block A has molecular weight of about 7,500 to about 20,000,the block copolymer comprises about 0.25 to about 25%, preferably about10 to about 20% wt. of the A blocks and about 50 to about 99.5%,preferably about 60 to about 80% wt. of the D blocks. After this blockcopolymer is polymerized, it is hydrogenated, so that the block D isselectively hydrogenated to such an extent that it containssubstantially none of the original unsaturation, while each of theblocks A retains a sufficient amount of the original unsaturation of theconjugated diene present in each of the A blocks to cure the blockcopolymer. The block copolymer of this embodiment is terminated at bothends with a block A.

Yet another embodiment is directed to a block copolymer comprising atleast three alternating blocks:

    I--D--A

where the blocks I, D and A are made from the same respective monomersdefined above, and the block A was molecular weight of about 350 toabout 7,500. The block copolymer comprises about 0.1 to about 50%,preferably about 1 to about 5% by weight (wt.) of the sum of blocks Iand A, and about 50 to about 99.9%, preferably about 95 to about 99% wt.of the block D.

The blocks A and I are referred to hereinafter as the "terminal blocks",and the blocks B and D as the "middle blocks".

Another embodiment of the invention is directed to a random copolymer ofat least one conjugated diene of formula (1) and at least one conjugateddiene of formula (3), both discussed above, provided that the diene offormula (3) is different from the diene of formula (1). This randomcopolymer contains about 0.1 to about 25, preferably about 0.1 to about5%, by mole of the polymerized conjugated diene of formula (1) and about75 to about 99.9, preferably about 95 to about 99.9%, by mole of theconjugated diene of formula (3). This random copolymer is alsoselectively hydrogenated so that the polymerized diene of formula (3)contains substantially none of the original unsaturation, while thepolymerized diene of formula (1) retains a sufficient amount of theoriginal unsaturation to cure the random copolymer.

Another embodiment of this invention is directed to random copolymers ofat least one aryl-substituted olefin, at least one conjugated diene offormula (1) and at least one conjugated diene of formula (3), bothdiscussed above, provided that the conjugated diene of formula (1) isdifferent from the conjugated diene of formula (3). This randomcopolymer contains about 0.1 to about 15% by mole of thearyl-substituted olefin, about 0.1 to about 25%, preferably about 0.1 toabout 5%, by mole of the conjugated diene of formula (1), and theremainder of the conjugated diene of formula (3). This random copolymeris also selectively hydrogenated, so that the polymerized diene offormula (3) contains substantially none of the original unsaturation,while the polymerized diene of formula (1) retains a sufficient amountof the original unsaturation to cure the random copolymer.

Yet another embodiment of the invention is directed to star-branchedblock and random polymers. The star-branched block polymers are madefrom any combination of blocks I and B, A and D, or I, D and A providingthat each free end (i.e., uncoupled end) of the star polymer is eitheran I or an A block, respectively. The star-branched block polymers areselectively hydrogenated to such an extent that blocks B or D containsubstantially none of the original unsaturation, while each of theblocks I or A, respectively, retains a sufficient amount of the originalunsaturation of the polymerized conjugated dienes present therein tocure the star-branched block polymers.

The star-branched random polymers are made from any combination ofdienes of formulae (1) and (3), providing that the diene of formula (3)is different from the diene of formula (1), or from at least onearyl-substituted olefin, a diene of formula (1) and a diene of formula(3), providing that the diene of formula (3) is different from the dieneof formula (1). The star-branched random polymers are selectivelyhydrogenated, so that the polymerized diene of formula (3) containssubstantially none of the original unsaturation, while the polymerizeddiene of formula (1) retains a sufficient amount of the originalunsaturation to cure the star-branched random polymers.

The copolymers of all embodiments are prepared under anionicpolymerization conditions. After the selective hydrogenation reaction,the hydrogenation catalyst is removed from the polymer.

In all embodiments of this invention, whenever a reference is made tothe "residual double bond" of the block or random polymer (orcopolymer), it is understood to be the residual double bond prior to theselective hydrogenation reaction. The structure of the residual doublebond can be determined in any conventional manner, as is known to thoseskilled in the art, e.g., by infrared (IR) analysis.

The term "original unsaturation", as used in this application, means thesum total of the unsaturated groups present in the copolymer prior tothe selective hydrogenation reaction. The unsaturation can be quantifiedin any conventional manner, e.g., by reference to the Iodine Number ofthe polymer. For example, for a triblock copolymer of the firstembodiment wherein the I blocks are polyisoprene and the B block ispolybutadiene, the Iodine Number before selective hydrogenation for eachof the I blocks is 373 and for the B block it is 470. After selectivehydrogenation is completed, the Iodine Number for each of the I blocksis about 37 to about 373, preferably about 93 to about 373, morepreferably about 186 to about 373, and most preferably about 373, andfor the B block it is about 0 to about 50, and preferably about 0 toabout 2.5.

In any polymers of any of the embodiments of this invention, themicrostructure of the polymerized conjugated diene of formula (3), e.g.,blocks B or D in the block copolymers, must be such that the polymer isnot excessively crystalline after the selective hydrogenation reaction,i.e., after the selective hydrogenation reaction, the polymer mustretain its elastomeric properties, e.g., the polymer should contain nomore than about 10% of polyethylene crystallinity. This is accomplishedby introducing side branches into the polymerized conjugated diene offormula (3), e.g., by controlling the microstructure of 1,3-butadiene ifit is the predominant monomer in the diene of formula (3), by using amixture of dienes of formula (3) containing less than predominantamounts of 1,3-butadiene, or by using a single diene of formula (3)other than 1,3-butadiene. More particularly, if the conjugated diene(s)of formula (3) is predominantly (at least 50% by mole) 1,3-butadiene,the side branches are introduced into the polymer by insuring that thepolymerized diene of formula (3) contains a sufficient amount of the1,2-units to prevent the selectively hydrogenated polymer from beingexcessively crystalline. Thus, if the conjugated diene of formula (3) ispredominantly (at least 50% by mole, e.g., 100% by mole) 1,3-butadiene,the polymerized diene of formula (3), prior to the selectivehydrogenation reaction, must contain not more than about 75% wt.,preferably about 10 to about 70% wt., and most preferably about 35 toabout 55% wt. of the 1,4-units (1,4-microstructure), and at least about25% wt., preferably about 30 to about 90% wt., and most preferably about45 to about 65% wt. of the 1,2-microstructure. If the polymerizeddiene(s) of formula (3) contains less than 50% by mole of 1,3-butadiene,e.g., 1,3-pentadiene is used as the only diene of formula (3), themicrostructure of the polymerized diene of formula (3) prior to theselective hydrogenation reactions is not critical since afterhydrogenation the resulting polymer will contain substantially nocrystallinity.

In all embodiments of the invention, mixtures of dienes of formulae (1)or (3) may be used to prepare block copolymers (I)_(x) --(B)_(y)--(I)_(x), (A)_(x) --(D)_(y) --(A)_(x) or I--D--A, any of the randomcopolymers or star-branched block and random polymers of this invention.Similarly, mixtures of aryl-substituted olefins may also be used toprepare block, random or star-branched copolymers of this invention.Accordingly, whenever a reference is made herein to a diene of formulae(1) or (3) or to an aryl-substituted olefin, it may encompass more thanone diene of formulae (1) or (3), respectively, and more than onearyl-substituted olefin.

DETAILED DESCRIPTION OF THE INVENTION

The block copolymers of this invention comprise three or morealternating blocks, identified above. However, block copolymers havingmore than three blocks are contemplated herein, although they do notappear to exhibit better properties than the block copolymers containingonly three blocks. In addition, star-branched block polymers containingany combination and number of blocks I and B, A and D or I, D and A arealso contemplated herein, providing that they are terminated either byblocks I or A. The middle block of each three block unit of the blockcopolymer is substantially completely saturated, while the terminalblocks contain controlled levels of unsaturation, providing ahydrocarbon elastomer with α-ω unsaturation. The length of the middlesaturated block defines the distance between crosslinks (M_(c)) in thevulcanized elastomers. Because of the α-ω placement of the unsaturation,very low levels of residual double bonds are required to attainexcellent vulcanization. The low level of unsaturation in theselectively hydrogenated tri-block polymer and its terminal positioningprovide excellent oxidative stability to the polymers of this invention.

Without wishing to be bound by any theory, it is believed that the α-ωplacement of unsaturation in the block polymers of this inventionimparts to the polymers excellent elastomeric properties which wereabsent in prior art thermosetting elastomers which required amultiplicity of relatively closely spaced crosslinks.

The combination of elastomeric properties and oxidative stabilitypossessed by the polymers of this invention makes them suitable for manyend uses, such as dynamically vulcanized thermoplastic elastomer blends,belts and hoses, white tire sidewalls, roofing, liners, impactmodifiers, mechanical goods, and ionic thermoplastic elastomers.

Many variations in composition, molecular weight, molecular weightdistribution, relative block lengths, microstructure, branching,crystallinity and Tg (glass transition temperature) attainable with theuse of the anionic techniques employed in the preparation of ourpolymers will be obvious to those skilled in the art.

While not wishing to limit the molecular weight range of solidelastomers prepared according to our invention, the minimum molecularweight for these solid polymers is at least about 15,000, preferably itis about 50,000 to about 2,000,000, more preferably about 80,000 toabout 250,000 and most preferably about 100,000. The block copolymers ofthis invention are vulcanizable. Without wishing to be bound by anytheory of operability, it is believed that they can be crosslinked (orvulcanized) in a controlled manner through the unsaturated groups on theterminal blocks to provide a very strong and orderly matrix ofcrosslinkages having almost uniform distribution of molecular weightsbetween crosslinks, M_(c). The random and star-branched copolymers ofthis invention are also vulcanizable. The designation M_(c), as usedherein for the block copolymers means the length of the middle block.For random copolymers, M_(c) is calculated by dividing number averagemolecular weight, M_(n), of the polymer by the average number ofcrosslinks per chain plus 1.

The invention will be described hereinafter in terms of the embodimentsthereof summarized above. However, it will be apparent to those skilledin the art, that the invention is not limited to these particularembodiments, but, rather, it covers all of the embodiments encompassedby the broadest scope of the description of the invention.

Block Copolymers From at Least Two Dissimilar Conjugated Dienes

In this embodiment of the invention, there is polymerized a blockcopolymer comprising at least three alternating blocks:

    (I).sub.x --(B).sub.y --(I).sub.x

wherein:

I is a block of at least one polymerized conjugated diene having atleast five (5) carbon atoms and the following formula ##STR5## whereinR¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided that at leastone of R¹ -R⁶ is a hydrocarbyl group, and further provided that thestructure of the residual double bond in the polymerized block I has thefollowing formula ##STR6## wherein R^(I), R^(II), R^(III) and R^(IV) areeach hydrogen or a hydrocarbyl group, provided that either both R^(I)and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups;

B is a block of at least one polymerized conjugated diene, differentfrom that used to polymerize block I, having at least four (4) carbonatoms and the following formula ##STR7## wherein R⁷ -R¹² are eachhydrogen or a hydrocarbyl group, provided that the structure of theresidual double bond in the polymerized block B has the followingformula ##STR8## wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen(H) or a hydrocarbyl group, provided that one of R^(a) or R^(b) ishydrogen, one of R^(c) or R^(d) is hydrogen and at least one of R^(a),R^(b), R^(c) or R^(d) is a hydrocarbyl group. In each of the I blocks, xis 1-100, preferably 2-100 and most preferably 2-30, i.e., each of the Iblocks is polymerized from 1-100, preferably from 2-100, and mostpreferably from 2-30 monomer units. For some special applications, eachof the I blocks is polymerized from 100-200 monomer units. The blockpolymers containing such large I blocks (i.e., containing 100-200monomer units) have increased vulcanization rate, as compared to thosecontaining smaller I blocks, and are co-vulcanizable with diene rubbersavailable in the art, e.g., polybutadiene and natural rubbers. The blockpolymers containing such large I blocks can be blended with dienerubbers by conventional methods and subsequently vulcanized to producenovel compositions of this invention. The resulting materials areexpected to have increased oxidation and ozone degradation resistance ascompared to known diene rubbers alone, and therefore are expected to bevaluable materials for the production of white sidewalls of tires andsimilar articles.

In each of the B blocks, y is 300 to 35,000 , preferably 1,000 to 5,000,and most preferably 1,500 to 4,000, i.e., each of the B blocks ispolymerized from 300 to 35,000, preferably from 1,000 to 5,000, and mostpreferably from 1,500 to 4,000 monomer units.

In the residual double bond of formula (2), R^(I), R^(II), R^(III) andR^(IV) may all be hydrocarbyl groups. The structures of the residualdouble bonds defined by formulae (2) and (4) are necessary to producecopolymers which can be selectively hydrogenated in the manner describedherein to produce the selectively hydrogenated block and randomcopolymers of this invention. The block copolymer comprises about 0.1 toabout 50%, preferably about 1 to about 5%, by wt. of the I blocks, andabout 50 to about 99.9%, preferably about 95 to about 99%, by wt. of theB blocks.

The hydrocarbyl group or groups in the formulae (1) and (2) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl or aralkyl groups or any isomersthereof. Suitable hydrocarbyl groups are alkyls of 1-20 carbon atoms,alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms,cycloalkenyls of 5-20 carbon atoms, aryls of 6-12 carbon atoms, alkarylsof 7-20 carbon atoms or aralkyls of 7-20 carbon atoms. Examples ofsuitable alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, decyl, methyl-decyl or dimethyldecyl. Examples ofsuitable alkenyl groups are ethenyl, propenyl, butenyl, pentenyl orhexenyl. Examples of suitable cycloalkyl groups are cyclohexyl ormethylcyclohexyl. Examples of suitable cycloalkenyl groups are 1-, 2-,or 3-cyclohexenyl or 4-methyl-3-cyclohexenyl. Examples of suitable arylgroups are phenyl or diphenyl. Examples of suitable alkaryl groups are4-methyl-phenyl (p-tolyl) or p-ethyl-phenyl. Examples of suitablearalkyl groups are benzyl or phenethyl. Suitable conjugated dienes offormula (1) used to polymerize the I block are isoprene,2,3-dimethyl-butadiene, myrcene, 2-methyl-1,3-pentadiene,3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene,3-phenyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene,2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene,2-p-tolyl-1,3-butadiene or mixtures thereof, preferably isoprene,myrcene or 2-methyl-1,3-pentadiene, and most preferably isoprene.

The hydrocarbyl group or groups in the formula (3) may or may not be thesame as those in formula (4). These hydrocarbyl groups are the same asthose described above in conjunction with the discussion of thehydrocarbyl groups of formulae (1) and (2). Suitable monomers for the Bblock are 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene,1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene,3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene,1,3-decadiene, 2,4-decadiene, 3,5-decadiene or mixtures thereof,preferably 1,3-butadiene, 1,3-pentadiene or 1,3-hexadiene, and mostpreferably it is 1,3-butadiene. It is preferred that each of the Bblocks is polymerized from a single monomer.

The block copolymer of this embodiment is terminated at both ends with ablock I.

The scope of this embodiment and of any other embodiments of theinvention wherein the block B is used also emcompasses polymers whereinthe central block B may be comprised of copolymers of one or moreconjugated diene of formula (3) and controlled amounts (about 0.1 toabout 30 mole %) of an aryl-substituted olefin, e.g., styrene or othersuitable monomers (such as alkylated styrene, vinyl napthalene oralkylated vinyl naphthalene), incorporated for control of glasstransition temperature (Tg), density, solubility parameters andrefractive index. Suitable aryl-substituted olefins are those describedbelow in conjunction with the second embodiment of the invention.Similarly, the scope of this embodiment also emcompasses polymerswherein the central block B may be comprised of copolymers of one ormore conjugated diene of formula (3) and any other anionicallypolymerizable monomer capable of polymerizing with the conjugated dieneof formula (3).

It will be apparent to those skilled in the art that proper choice ofpolymerization parameters can produce polymers with a great variety ofcompositional and structural differences, falling within the scope ofour invention. Changes in composition of the central block B control thenature of the rubbery properties while changes in the terminal blockspermit response to different vulcanizing agents, e.g., sulfur-based curesystems and phenolic resin cure systems.

The block copolymer is polymerized by any conventional blockcopolymerization process, such as anionic polymerization, discussed indetail below. As will be apparent to those skilled in the art, thecopolymer of this embodiment contains at least three alternating blocks,I--B--I, referred to herein as the triblocks or triblock units, but itmay contain an unlimited number of blocks, so long as the entire blockcopolymer is terminated at both ends by the I blocks. It is, however,preferred that the copolymer of this embodiment contain only onetriblock I--B--I. Polymers having more than three blocks (such as five)allow crosslinking to take place at the ends and in the central portion,but maintain a controlled large distance between crosslinks of thepolymer. It is important to have the block copolymer terminated at eachend with the I blocks to assure that there are unsaturated groups ateach end of the block copolymer enabling the block copolymer to becross-linked or functionalized at the terminal ends thereof. The term"functionalized" is used herein to describe chemical modifications ofthe unsaturated groups to produce functional groups, the nature of whichis described in detail below. The crosslinking of the functionalized andnonfunctionalized copolymer chains is conducted in a conventional mannerand is described below.

After the block copolymer is polymerized, it is subjected to a selectivehydrogenation reaction during which the B blocks of the block copolymerare selectively hydrogenated to such an extent that they containsubstantially none of the original unsaturation, while the I blocksretain a sufficient amount of their original unsaturation to cure theblock copolymer. Generally, for a block copolymer wherein the I and Bblocks are polymerized from any of the monomers discussed above, theIodine Number for the I blocks after the selective hydrogenationreaction is about 10 to about 100%, preferably about 25 to about 100%,more preferably about 50 to about 100%, and most preferably about 100%of the Iodine Number prior to the selective hydrogenation reaction, andfor the B blocks it is about 0 to about 10%, preferably about 0 to about0.5%, of the Iodine Number prior to the selective hydrogenationreaction. The Iodine Number, as is known to those skilled in the art, isdefined as the theoretical number of grams of iodine which will add tothe unsaturation in 100 grams of olefin and is a quantitativemeasurement of unsaturation.

In this embodiment of the invention, although the microstructure of theI blocks is not critical and may consist of any combination of 1,2-,3,4-and 1,4-units, schematically represented below for the polyisopreneblocks, when a polar compound is used during the polymerization of the Iblock, the I blocks comprise primarily (at least about 80%) 3,4-units,the remainder being primarily (about 20%) 1,2-units; when the polarcompound is not used during the polymerization of the I block, the Iblocks comprise primarily (about 80%) 1,4-units, the remainder beingprimarily 1,2-and 3,4-units. ##STR9##

As discussed above, when the predominant monomer used to polymerize theB blocks is 1,3-butadiene, the microstructure of the B blocks should bea mixture of 1,4- and 1,2- units schematically shown below for thepolybutadiene blocks: ##STR10## since the hydrogenation of thepredominantly 1,4-microstructures produces a crystalline polyethylenesegment. The microstructure of the I and B blocks (as well as of thepolymerized conjugated dienes of formulae (1) or (3) in any polymers ofthis invention) is controlled in a conventional manner, e.g., bycontrolling the amount and nature of the polar compounds used during thepolymerization reaction, and the reaction temperature. In oneparticularly preferred embodiment, the polybutadiene block containsabout 55% of the 1, 2-and about 45% wt. of the 1,4-microstructure. Ifthe B block is polybutadiene, the hydrogenation of the B blockcontaining about 50 to about 60% wt. of the 1,2-microstructure contentproduces an elastomeric center block which is substantially anethylene-betene-1 copolymer having substantially no crystallinity. Thereduction of the 1,2-content microstructure in the polybutadiene blockin a controlled manner permits the introduction of controlled levels ofcrystallinity into the hydrogenated polybutadiene block which provides a"green" (unvulcanized) strength necessary in certain applications. Ifthe B block is polymerized from 1,3-pentadiene, it is preferred that ithave predominantly (at least 50%) 1,4-microstructure, which, afterhydrogenation, produces a substantially non-crystalline elastomericblock.

The terms 1,2-, 1,4-, and 3,4-microstructure or units as used in thisapplication refer to the products of polymerization obtained,respectively, by the 1,2-, 1,4- and 3,4-, additions of monomer unitsinto the growing polymer chain.

We surprisingly discovered that the polymerized conjugated dienes offormula (3), e.g., the B blocks, of the polymers of this invention areselectively hydrogenated in our hydrogenation process much faster thanthe polymerized conjugated dienes of formula (1), e.g., the I blocks.This is not evident from the teachings of Falk, discussed above, becauseFalk teaches that double bonds of the disubstituted 1,4-polybutadieneunits are hydrogenated selectively in the presence of double bonds ofthe trisubstituted 1,4-polyisoprene units (which are not hydrogenated).We suprisingly discovered that the disubstituted double bonds of the1,4-polybutadiene units are hydrogenated along with the monosubstituteddouble bonds of the 1,2-polybutadiene units, while the disubstituteddouble bonds of the 3,4-polyisoprene units are hydrogenated at a muchslower rate than the aforementioned butadienes. Thus, in view of Falk'sdisclosure it is surprising that the disubstituted double bonds of the1,4-polybutadiene units are hydrogenated selectively in the presence ofthe disubstituted double bonds of the 3,4-polyisoprene units. This isalso surprising in view of the teachings of Hoxmeier, Published EuropeanPatent Application, Publication No. 0 315 280, who discloses that thedisubstituted double bonds of the 1,4-polybutadiene units,monosubstituted double bonds of the 1,2-polybutadiene units anddisubstituted double bonds of the 3,4-polyisoprene units arehydrogentated simultaneously at substantially the same rates. Forexample, for the block copolymers of this invention, wherein the I blockis polyisoprene and the B block is polybutadiene, Fourier transforminfrared (FTIR) analysis of selectively hydrogenated triblock polymersindicates that the hydrogenation of the double bonds of the1,2-polybutadiene units proceeds most rapidly, followed by thehydrogenation of the double bonds of the 1,4-polybutadiene units.Infrared absorptions caused by these groups disappear prior toappreciable hydrogenation of the polyisoprene units.

After the I--B--I block copolymer is prepared, it is subjected to aselective hydrogenation reaction to hydrogenate primarily only themiddle B unit of each of the triblocks. The selective hydrogenationreaction and the catalyst are described in detail below. After thehydrogenation reaction is completed, the selective hydrogenationcatalyst is removed from the block copolymer, and the polymer isisolated by conventional procedures, e.g., alcohol flocculation, steamstripping of solvent or non-aqueous solvent evaporation. An antioxidant,e.g., Irganox 1076 (from Ciba-Geigy), is normally added to the polymersolution prior to polymer isolation.

The isolated polymer is vulcanizable through the unsaturated end blocksI by a number of well known processes utilized currently forthermosetting hydrocarbon elastomers. Such processes are detailed inRUBBER TECHNOLOGY, THIRD EDITION, VAN NOSTRAND REINHOLD COMPANY, NewYork, 1987. Maurice Morton, Editor, chapters 2,9 and 10, incorporatedherein by reference Triblock Copolymer of at Least One Poly-Diene CenterBlock and Terminal Blocks of Aryl-Substituted Olefin/Diene Copolymer

In this alternative embodiment of the invention, the block copolymercomprises at least one triblock of:

    (A).sub.x --(D).sub.y --(A).sub.x

wherein the block A is a copolymer of at least one aryl-substitutedolefin and at least one conjugated diene of formula (1), defined above.The block A is either a random or a block copolymer. When the block Ahas molecular weight of about 350 to about 7,500, it comprises about 50to about 65%, preferably about 50% by mole of the aryl-substitutedolefin, and about 35% to about 50%, preferably about 50% by mole of theconjugated diene of formula (1). When the block A has molecular weightof about 7,500 to about 20,000, it comprises about 1 to about 99%,preferably about 80 to about 98% by mole of the aryl-substituted olefin,and about 99 to about 1%, preferably about 2 to about 20% by mole of theconjugated diene of formula (1). When the block A has molecular weightof about 350 to about 7,500, x represents the total number of monomerunits in the block A, such that the block copolymer comprises about 0.25to about 10%, preferably about 2 to about 10% wt. of the A blocks, and yrepresents the total number of monomer units in the block D, such thatthe block copolymer comprises about 80 to about 99.5%, preferably about80 to about 96% wt. of the D blocks. When the block A has molecularweight of about 7,500 to about 20,000, the block copolymer comprisesabout 0.25 to about 25%, preferably about 10 to about 20% wt. of the Ablocks and about 50 to about 99.5%, preferably about 60 to about 80% wt.of the D blocks. The most preferred conjugated diene of formula (1) isisoprene. In this block copolymer, D is a block of a polymer of at leastone conjugated diene of formula (3), discussed above, which is differentfrom the conjugated diene of formula (1). The block copolymer of thisembodiment may contain several, e.g., 5-7, blocks of the aforementionedformula so long as it is terminated at both ends with the block A, but,preferably, it contains only three blocks A--D--A. Suitablearyl-substituted olefins used to polymerize the A block have the formula##STR11## where Ar is phenyl, alkyl-substituted phenyl, naphthyl oralkyl-substituted naphthyl, R^(e) is hydrogen, methyl, ethyl, propyl,butyl or aryl. Examples of suitable aryl-substituted olefins arestyrene, 2-phenyl alpha-olefins, such as alpha-methyl styrene,1,1-diphenyl ethylene, alkylated styrenes, vinyl naphthalene, or anyalkylated vinyl naphthalenes. Suitable alkyl substituents in thealkylated styrenes or alkylated vinyl naphthalenes are methyl, ethyl,propyl, tert-butyl and sec-butyl. Each of the alkylated styrenes orvinyl naphthalenes may contain one or more alkyl substituents. Preferredaryl-substituted olefins are styrene, vinylnapthalene, alpha-methylstyrene, vinyltoluene and diphenylethylene. The microstructure of thepolymerized diene of formula (1) is not critical, but can be controlledin the manner discussed above. In the most preferred embodiment, the Ablock of this triblock copolymer is polymerized from isoprene andstyrene in the molar proportion of about 1:10. The block copolymer ispolymerized by any conventional block copolymerization process, such asanionic polymerization, discussed in detail below.

Regardless of the molecular weight of the block A, the scope of thisembodiment, and of any other embodiment of the invention wherein theblock A is used, also emcompasses polymers wherein the blocks A areprepared by, initially, polymerizing at least one aryl-substitutedolefin alone, and subsequently reacting the resultingpoly-aryl-substituted olefin with any compounds which, after chemicalreaction with the poly-aryl-substituted olefin, will provide theresidual double bonds to the A blocks, as defined above in conjunctionwith the discussion of the conjugated diene of formula (1). Theresulting block A will therefore have substantially the same residualunsaturation (residual double bonds) on the terminal blocks A as anyother block A made in accordance with this embodiment (or any otherembodiment which uses the block A), i.e., by copolymerizing thearyl-substituted olefin with at least one conjugated diene of formula(1).

The block copolymer of this embodiment is terminated at both ends with ablock A.

The scope of this embodiment, and of any other embodiments of theinvention wherein the block D is used, also emcompasses polymers whereinthe central (middle) block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and controlled amounts (about 0.1to about 30 mole %) of an aryl-substituted olefin, e.g., styrene orother suitable monomers (such as alkylated styrene, vinyl napthalene oralkylated vinyl naphthalene), incorporated for control of glasstransition temperature (Tg), density, solubility parameters andrefractive index.

Most preferably, in this embodiment of the invention, the block A of thecopolymer has molecular weight of about 7,500 to about 20,000, the Ablock is polymerized from isoprene and styrene, and the D block from1,3-butadiene, in such proportions that the final copolymer comprisesabout 1 to about 2% wt. of the isoprene, about 25 to about 36% wt. ofthe styrene, and about 62 to about 74% wt. of the butadiene units.

After the polymerization is completed, the block copolymer is subjectedto a selective hydrogenation reaction. After selective hydrogenation,the polymer contains a sufficient amount of its original unsaturation inthe terminal blocks A to cure the block copolymer, thereby permittingchemical crosslinking or functionalization in the manner discussedbelow, while the middle block D contains substantially none of theoriginal unsaturation. For example, for a block copolymer wherein the Ablocks are copolymers of styrene and isoprene and the D block ispolybutadiene, the Iodine Number before selective hydrogenation for eachof the A blocks is 5-150 and for the D block it is 250-470. Afterselective hydrogenation, the Iodine Number for each of the A blocks isabout 5 to about 150 and for the D block it is about 0 to about 10,preferably about 0 to about 2.5, and most preferably 0. Generally, for ablock copolymer wherein the A and D blocks are polymerized from any ofthe monomers suitable for their polymerization, discussed above, theIodine Number for the A blocks after the selective hydrogenation iscompleted is about 10 to about 100%, preferably about 100% of the IodineNumber prior to the selective hydrogenation reaction, and for the Dblocks it is about 0 to about 10%, preferably about 0 to about 0.5%, andmost preferably 0% of the Iodine Number prior to the selectivehydrogenation reaction. Thus, in this embodiment, the block D is alsoselectively hydrogenated in the same manner as discussed above for thecentral block B of the first embodiment of the invention.

The block copolymer of this embodiment is also a solid, and, afterselective hydrogenation, the unsaturated groups in the terminal A blocksof each of the triblocks provide a means of crosslinking the copolymeror functionalizing the terminal blocks A, in the manner discussedelsewhere in this application.

The preferred polymers of this embodiment, wherein the A blocks havemolecular weights of about 7,500 to aout 20,000, while possessing thesuperior elastomeric properties of the thermoplastic elastomer triblocksin the uncured state, can be chemically crosslinked to render theminsoluble in most organic solvents and enable them to retain elastomericproperties at very high temperatures. This elastomer is distinct fromKRATON since KRATON has no unsaturated groups in the terminal styreneblocks and therefore cannot be chemically cross-linked through theseblocks.

Triblock Copolymer of at Least One Poly-Diene Center Block. and at LeastOne Terminal Block of Aryl-Substituted Olefin/Diene Copolymer

In this embodiment of the invention, the block copolymer comprises atleast one triblock of:

    I--D--A

where the block I is a polymer of at least one polymerized diene offormula (1), defined above, the block D is a polymer of at least oneconjugated diene of formula (3), defined above, which is different fromthe conjugated diene of formula (1), and the block A is a copolymer ofat least one aryl-substituted olefin and at least one conjugated dieneof formula (1), both defined above. The block A has molecular weight ofabout 350 to about 7,500 and it comprises about 50 to about 65%,preferably about 50% by mole of the aryl-substituted olefin, and about35 to about 50, preferably about 50% by mole of the conjugated diene offormula (1). This block copolymer comprises about 0.1 to about 50,preferably about 1 to about 5% wt. of the sum of blocks I and A, andabout 50 to about 99.9, preferably about 95 to about 99% wt. of theblock D. The block copolymer of this embodiment may also containseveral, e.g. 5-7, blocks of the aforementioned formulae so long as itis terminated at both ends thereof with blocks I or A. The blockcopolymer is polymerized by any conventional block copolymerizationprocess, such as anionic polymerization, discussed in detail below.

The scope of this embodiment of the invention also encompasses polymerswherein the central block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and controlled amounts (about 0.1to about 30 mole %) of an aryl-substituted olefin, e.g., styrene orother suitable monomers (such as alkylated styrene, vinyl napthalene oralkylated vinyl naphthalene), incorporated for control of glasstransition temperature (Tg), density, solubility parameters andrefractive index. Suitable aryl-substituted olefins are those describedabove. Similarly, the scope of this embodiment also emcompasses polymerswherein the central block D may be comprised of copolymers of one ormore conjugated diene of formula (3) and any other anionicallypolymerizable monomer capable of polymerizing with the conjugated dieneof formula (3). This embodiment also encompasses polymers wherein theblocks A are prepared by, initially, polymerizing at least onearyl-substituted olefin alone and, subsequently, reacting the resultingpoly-aryl-substituted olefin with any compounds which, after chemicalreaction with the poly-aryl-substituted olefin, will provide theresidual double bonds to the A blocks, as defined above in conjunctionwith the discussion of the conjugated diene of formula (1). Theresulting block A will therefore have substantially the same residualunsaturation (residual double bonds) on the terminal blocks A as anyother block A made in accordance with this embodiment.

After the polymerization is completed the block copolymer is subjectedto a selective hydrogenation reaction. After selective hydrogenation,the polymer contains a sufficient amount of its original unsaturation inthe terminal blocks I and A to cure the block copolymer, therebypermitting chemical crosslinking or functionalization in the mannerdiscussed below, while the middle block D contains substantially none ofthe original unsaturation. Generally, for a block copolymer wherein theI, D and A blocks are polymerized from any of the monomers suitable fortheir polymerization, as defined above, the Iodine Number for the I andA blocks after the selective hydrogenation is completed is about 10 toabout 100%, preferably about 100% of the Iodine Number prior to theselective hydrogenation reaction, and for the D blocks it is about 0 toabout 10%, preferably about 0 to about 0.5%, and most preferably 0% ofthe Iodine Number prior to the selectice hydrogenation reaction. Thus,in this embodiment, the block D is also selectively hydrogenated in thesame manner as discussed above, while the terminal blocks I and A retaina substantial amount of their original unsaturation.

The block copolymer of this embodiment is also a solid, and, afterselective hydrogenation, the unsaturated groups in the terminal I and Ablocks of each of the triblocks provide a means of crosslinking thecopolymer or functionalizing the terminal blocks I and A, in the mannerdiscussed elsewhere in this application.

Random Copolymers

Random copolymers of this invention have controlled amounts ofunsaturation incorporated randomly in an otherwise saturated backbone.In contrast to EPDM, the level of unsaturation can be inexpensively andeasily controlled, e.g., to produce polymers having Iodine Number ofabout 5 to about 100, to provide a wide variation in vulcanization rateand potential co-curability with various highly unsaturated rubbersbased on butadiene or isoprene.

In one embodiment, the random copolymers are polymerized from the samemonomers used to polymerize the block copolymers (I)_(x) --(B)_(y)--(I)_(x), i.e., from at least one conjugated diene of formula (1) andat least one conjugated diene of formula (3), both defined above,providing that the diene of formula (1) is different from the diene offormula (3). This random copolymer contains about 1.0 to about 25%,preferably about 1.0 to about 10% by mole of the polymerized conjugateddiene of formula (1) and about 75 to about 99%, preferably about 90 toabout 99% by mole of the polymerized conjugated diene of formula (3).Suitable conjugated dienes of formula (1) are exemplified above. Themost preferred conjugated diene of formula (1) for the copolymerizationof these random copolymers is isoprene. Suitable conjugated dienes offormula (3) are also exemplified above. 1,3-butadiene is the mostpreferred conjugated diene of formula (3) for the polymerization of therandom copolymer of this embodiment. Thus, most preferably, in thisembodiment, the random copolymer is polymerized from isoprene and1,3-butadiene, and it contains about 1 to about 20% wt. of the isopreneunits and about 80 to about 99% wt. of the butadiene units. The isopreneunits have primarily (i.e., about 50 to about 90% wt.) the3,4-microstructure.

In another embodiment, the random copolymers are polymerized from thesame monomers used to polymerize the block copolymers (A)_(x) --(D)_(y)--(A)_(x), i.e., from at least one aryl-substituted olefin, at least oneconjugated diene of formula (1), and at least one conjugated diene offormula (3), providing that the conjugated diene of formula (1) isdifferent from the conjugated diene of formula (3) used in thepolymerization. The conjugated dienes of formulae (1) and (3) and thearyl-substituted olefins are defined above. This alternative randomcopolymer contains about 0.3 to about 15% by mole of thearyl-substituted olefin, about 1.0 to about 25%, preferably about 1.0 toabout 10%, by mole of the conjugated diene of formula (1), the remainderbeing the conjugated diene of formula (3).

The random copolymers are then subjected to the selective hydrogenationreaction discussed above for the block copolymers, during whichpolymerized conjugated diene units of formula (3) are substantiallycompletely hydrogenated, while the polymerized conjugated diene units offormula (1) are hydrogenated to a substantially lesser extent, i.e., tosuch an extent that they retain a sufficient amount of their originalunsaturation to vulcanize the copolymer, thereby producing solidelastomers having random unsaturation proportional to the unsaturationin the polymerized dienes of formula (1). For example, for a randomcopolymer polymerized from a diene of formula (1) and a different dieneof formula (3), the Iodine Number before selective hydrogenation for thepolymer is about 450. After selective hydrogenation, the Iodine Numberfor the polymer is about 10 to about 100, most of the unsaturation beingcontributed by the diene of formula (1). Generally, in such randomcopolymers, the Iodine Number for the polymerized dienes of formula (1)after the selective hydrogenation reaction is about 10 to about 100%,preferably about 25 to about 100%, more preferably about 50 to about100%, and most preferably about 100% of the Iodine Number prior to theselective hydrogenation reaction, and for the polymerized dienes offormula (3) it is about 0 to about 10%, preferably about 0 to about 0.5%of the Iodine Number prior to the selective hydrogenation reaction. TheIodine Number for the polymerized dienes of formulae (1) and (3) beforeand after the hydrogenation reactions in these random copolymers can beestimated by any conventional techniques, e.g., by Fourier TransformInfrared (FTIR) analysis, as will be apparent to those skilled in theart.

Similarly, for a random copolymer of aryl-substituted olefins, aconjugated diene of formula (1) and a conjugated diene of formula (3),different from the conjugated diene of formula (1), the Iodine Numberbefore selective hydrogenation for the polymer is about 300 to about450. After selective hydrogenation, the Iodine Number for the polymer isabout 5 to about 100, most of the unsaturation measured by the IodineNumber being contributed by the polymerized diene of formula (1).Generally, for the random copolymer of this embodiment the Iodine Numberafter the selective hydrogenation reaction for the polymerized diene offormula (1) is about 10 to about 100%, preferably about 100% of theIodine Number prior to the selective hydrogenation reaction, and for thepolymerized diene of formula (3) it is about 0 to about 100%, preferablyabout 0% of the Iodine Number prior to the selective hydrogenationreaction.

The hydrogenated polymers may be vulcanized. The vulcanized randomcopolymers of this invention have elastomeric properties similar tothose of EPDM. The vulcanization rate of the polymers can be easily andinexpensively increased by increasing the content of the diene offormula (1), i.e., isoprene in the most preferred embodiment, in eitherembodiment of the random copolymers to from about 5 to about 20% mole.

Star-Branched Polymers

The invention is also directed to star-branched block and randompolymers.

The star-branched block polymers are made from any combination of blocksI and B, A and D, or I, D and A, defined above, providing that each freeend (i.e., the uncoupled end) of the star-branched polymer is either anI or an A block in the star-branched block polymers made from blocks Iand B, A and D or I, D and A. The star-branched I--B block copolymerscomprise about 0.1 to about 50%, preferably about 1 to about 5% by wt.of the I blocks and about 50 to about 99.9% by wt. of the B blocks. Thestar-branched A--D block copolymers, similarly to the A--D--A blockcopolymers, may have the A blocks of a low molecular weight (about 350to about 7,500) or of a high molecular weight (about 7,500 to about20,000). When the block A has molecular weight of about 350 to about7,500, it comprises about 50 to about 65%, preferably about 50% by moleof the aryl-substituted olefin, and about 35% to about 50%, preferablyabout 50% by mole of the conjugated diene of formula (1). When the blockA has molecular weight of about 7,500 to about 20,000, it comprisesabout 1 to about 99%, preferably about 80 to about 98% by mole of thearyl-substituted olefin, and about 99 to about 1%, preferably about 2 toabout 20% by mole of the conjugated diene of formula (1). When the blockA has molecular weight of about 350 to about 7,500, the A--Dstar-branched block copolymer comprises about 0.25 to about 10%,preferably about 2 to about 10% wt. of the A blocks, and about 80 toabout 99.5%, preferably about 80 to about 96% wt. of the D blocks. Whenthe block A has molecular weight of about 7,500 to about 20,000, theA--D star-branched block copolymer comprises about 0.25 to about 25%,preferably about 10 to about 20% wt. of the A blocks and about 50 toabout 99.5%, preferably about 60 to about 80% wt. of the D blocks. Inthe star-branched I--D--A block copolymers, the block A has molecularweight of about 350 to about 7,500. The star-branched I--D--A blockcopolymers comprise about 0.1 to about 50%, preferably about 1 to about5% wt. of the sum of blocks I and A, and about 50 to about 99.9%,preferably about 95 to about 99% wt. of the blocks D.

The star-branched block polymers are selectively hydrogenated in theselective hydrogenation process to such an extent that blocks B or Dcontain substantially none of the original unsaturation, while each ofthe blocks I and A, respectively, retains a sufficient amount of theoriginal unsaturation of the conjugated dienes present in these blocksto cure the star-branched block polymers. Thus, for the I--Bstar-branched block polymer, after the selective hydrogenation reaction,the Iodine Number for the I blocks is about 10 to about 100%, preferablyabout 25 to about 100%, more preferably about 50 to about 100%, and mostpreferably about 100% of their Iodine Number prior to the selectivehydrogenation reaction, and for the B blocks it is about 0 to about 10%,preferably about 0 to about 0.5% of the Iodine Number prior to theselective hydrogenation reaction. For the A--D star-branched blockpolymer, after the selective hydrogenation reaction, the Iodine Numberfor the A blocks is about 10 to about 100%, preferably about 25 to about100%, more preferably about 50 to about 100%, and most preferably about100% of the Iodine Number prior to the selective hydrogenation reaction,and for the D blocks it is about 0 to about 10%, preferably about 0 toabout 0.5% of the Iodine Number prior to the selective hydrogenationreaction. Similarly, for the I--D--A star-branched block polymer, theIodine Number for each of the I and A blocks after the selectivehydrogenation is completed is about 10 to about 100%, preferably about100% of the Iodine Number prior to the selective hydrogenation reaction,and for the D blocks it is about 0 to about 10%, preferably about 0 toabout 0.5%, and most preferably 0% of the Iodine Number prior to theselective hydrogenation reaction. Thus, in this embodiment, the block Dis also selectively hydrogenated in the same manner as discussed abovefor the central blocks B and D of the other embodiments of theinvention.

The star-branched random copolymers are made from any combination of atleast one diene of formula (1) and at least one diene of formula (3), orfrom any combination of at least one aryl-substituted olefin, at leastone diene of formula (1) and at least one diene of formula (3), all ofwhich are the same as those discussed above in conjunction with theblock and random copolymers. The star-branched random copolymers of thedienes of formulae (1) and (3), which must be different from each other,comprise about 1 to about 25%, preferably about 1 to about 10% by moleof the polymerized conjugated diene of formula (1) and about 75 to about99%, preferably about 90 to about 99% by mole of the polymerizedconjugated diene of formula (3). The star-branched random copolymers ofthe aryl-substituted olefin, at least one diene of formula (1) and atleast one diene of formula (3), different from the diene of formula (1),comprise about 0.3 to about 15% by mole of the aryl-substituted olefin,about 1 to about 25%, preferably about 1 to about 10% by mole of theconjugated diene of formula (1), and the remainder of the conjugateddiene of formula (3). The star-branched random copolymers are alsoselectively hydrogenated in the selective hydrogenation process to suchan extent that the polymerized dienes of formula (3) containsubstantially none of the original unsaturation, while the polymerizeddienes of formula (1) retain a sufficient amount of the originalunsaturation to cure the star-branched random copolymers. Thus, for thestar-branched random polymer of the conjugated diene of formula (1) anda different diene of formula (3), both identified above, the IodineNumber for the polymerized diene of formula (1), after the selectivehydrogenation reaction, is about 10 to about 100%, preferably about 25to about 100%, more preferably about 50 to about 100%, and mostpreferably about 100% of the Iodine Number prior to the selectivehydrogenation reaction, and for the polymerized diene of formula (3) itis about 0 to about 10%, preferably about 0 to about 0.5% of the IodineNumber prior to the selective hydrogenation reaction. Similarly, for thestar-branched random polymers made from at least one aryl-substitutedolefin, at least one diene of formula (1) and at least one diene offormula (3), the Iodine Number for the polymerized diene of formula (1),after the selective hydrogenation reaction, is about 10 to about 100%,preferably about 25 to about 100%, more preferably about 50 to about100%, and most preferably about 100% of the Iodine Number prior to theselective hydrogenation reaction, and for the polymerized diene offormula (3) it is about 0 to about 10%, preferably about 0 to about 0.5%of the Iodine Number prior to the selective hydrogenation reaction.

Blends Of Inventive Polymers With Other Materials

The block or random copolymers of this invention can, of course, beblended with any rubbers, in which case the degree of unsaturation ofthe copolymers of the invention can be adjusted so that thevulcanization rate of the two materials is substantially the same.Suitable rubbers which can be blended with the copolymers of thisinvention are EPDM, butyl rubber and rubbers based on butadiene orisoprene.

The block and random copolymers of this invention can also be blendedwith plastics, e.g., isotactic polypropylene, pooystyrene, polyethylene,Nylon, polycarbonates, polyesters and styrene-acrylonitrile resins.Thermoplastic elastomers having excellent properties can be obtained bydynamically vulcanizing a blend of polypropylene and the elastomers ofour invention, in which the elastomers are crosslinked to a very highdegree. A commercial material, Santoprene (trademark of and produced byMonsanto Chemical Co.) is based upon blends of polypropylene and EPDM.Details of the preparation and properties of such blends are presentedin THERMOPLASTIC ELASTOMERS, A COMREHENSIVE REVIEW, edited by N. R.Legge et al., Chapter 7, Hanser Publishers, Munich, Vienna and New York(1987), the contents of which are incorporated herein by reference. Suchdynamically vulcanized blends prepared with the polymers of theinvention in a conventional manner, e.g., that of N. R. Legge et al.,wherein the polymers of this invention are blended with polypropylene,and most particularly wherein the triblock polymers of this inventionare blended with polypropylene, can provide thermoplastic elastomerswith unique elastomeric properties.

The block and random copolymers of this invention can, of course, becompounded with ingredients known to those skilled in the art, e.g.,fillers, such as silica, carbon block, extender oils, antioxidants,tackifying agents, vulcanizing agents and similar materials.

Polymerization Reaction

The block copolymers of this invention are polymerized by any knownblock polymerization processes, preferably by an anionic polymerizationprocess. Anionic polymerization is well known in the art, and it isutilized in the production of a variety of commercial polymers. Anexcellent comprehensive review of the anionic polymerization processesappears in the text ADVANCES IN POLYMER SCIENCE 56, ANIONICPOLYMERIZATION, pp. 1-90, Springer-Verlag, Berlin, Heideberg, New York,Tokyo 1984 in a monograph entitled ANIONIC POLYMERIZATION OF NON-POLARMONOMERS INVOLVING LITHIUM, by R. N. Young, R. P. Quirk and L. J.Fetters, incorporated herein by reference. The anionic polymerizationprocess is conducted in the presence of a suitable anionic catalyst(also known as an initiator), such as n-butyl-lithium,sec-butyl-lithium, t-butyl-lithium, sodium naphthalide or cumylpotassium. The amount of the catalyst and the amount of the monomer inthe polymerization reaction dictate the molecular weight of the polymer.The polymerization reaction is conducted in solution using an inertsolvent as the polymerization medium, e.g., aliphatic hydrocarbons, suchas hexane, cyclohexane or heptane, or aromatic solvents, such as benzeneor toluene. In certain instances, inert polar solvents, such astetrahydrofuran, can be used alone as a solvent, or in a mixture with ahydrocarbon solvent.

The block polymerization process will be exemplified below for thepolymerization of the first embodiment of the invention, andspecifically for the preferred embodiment thereof, i.e., a triblock ofpolyisoprene-polybutadiene-polyisoprene. However, it will be apparent tothose skilled in the art that the same process principles can be usedfor the polymerization of all copolymers of the invention.

The process, when using a lithium-based catalyst, comprises forming asolution of the isoprene monomer in an inert hydrocarbon solvent, suchas cyclohexane, modified by the presence therein of one or more polarcompounds selected from the group consisting of ethers, thioethers andtertiary amines, e.g., tetrahydrofuran. The polar compounds arenecessary to control the microstructure of the butadiene center block,i.e., the content of the 1,2-structure thereof. The higher the contentof the polar compounds, the higher will be the content of the1,2-structure in these blocks. Since the presence of the polar compoundis not essential in the formation of the first polymer block with manyinitiators unless a high 3,4-structure content of the first block isdesired, it is not necessary to introduce the polar compound at thisstage, since it may be introduced just prior to or together with theaddition of the butadiene in the second polymerization stage. Examplesof polar compounds which may be used are dimethyl ether, diethyl ether,ethyl methyl ether, ethyl propyl ether, dioxane, diphenyl ether,tripropyl amine, tributyl amine, trimethyl amine, triethyl amine, andN-,N-,N'-,N'-tetramethyl ethylene diamine. Mixtures of the polarcompounds may also be used. The amount of the polar compound depends onthe type of the polar compound and the polymerization conditions as willbe apparent to those skilled in the art. The effect of the polarcompounds on the polybutadiene microstructure is detailed in ANTKOWIAKet al. TEMPERATURE AND CONCENTRATION EFFECTS ON POLAR-MODIFIED ALKYLLITHIUM POLYMERIZATIONS AND COPOLYMERIZATIONS, JOURNAL OF POLYMERSCIENCE: Part A-1, Vol. 10, 1319-1334 (1972), incorporated herein byreference. The polar compounds also accelerate the rate ofpolymerization. If monomers other than butadiene, e.g., pentadiene, areused to polymerize the central blocks B or C, polar compounds are notnecessary to control the miscrostructure because such monomers willinherently produce polymers which do not possess crystallinity afterhydrogenation.

When the alkyl lithium-based initiator, a polar compound and an isoprenemonomer are combined in an inert solvent, polymerization of the isopreneproceeds to produce the first terminal block whose molecular weight isdetermined by the ratio of the isoprene to the initiator. The "living"polyisoprenyl anion formed in this first step is utilized as thecatalyst for further polymerization. At this time, butadiene monomer isintroduced into the system and block polymerization of the second blockproceeds, the presence of the polar compound now influencing the desireddegree of branching (the 1,2-structure content) in the polybutadieneblock. The resulting product is a living diblock polymer having aterminal anion and a lithium counterion. The living diblock polymerserves as a catalyst for the growth of the final isoprene block, formedwhen isoprene monomer is again added to the reaction vessel to producethe final polymer block, resulting in the formation of the I--B--Itriblock. Upon completion of polymerization, the living anion, nowpresent at the terminus of the triblock, is destroyed by the addition ofa proton donor, such as methyl alcohol or acetic acid. Thepolymerization reaction is usually conducted at a temperature of between0° C. and about 100° C., although higher temperatures can be used.Control of a chosen reaction temperature is desirable since it caninfluence the effectiveness of the polar compound additive incontrolling the polymer microstructure. The reaction temperature can be,for example, from 50° to 80° C. The reaction pressure is not criticaland varies from atmospheric to about 100 psig. If the polar compoundsare utilized prior to the polymerization of the first I segment, Iblocks with high 3,4-unit content are formed. If polar compounds (someof which can be Lewis bases) are added after the initial I segment isprepared, the first I segment will possess a high percentage of1,4-microstructure (which is trisubstituted), and the second I segmentwill have a high percentage of 3,4-microstructure.

The production of triblock polymers having a high 1,4-unit content onboth of the terminal I blocks is also possible by the use of couplingtechniques illustrated below for apolyisoprene-polybutadiene-polyisoprene block copolymer: ##STR12## Thesubstitution of myrcene for the isoprene during the polymerization ofthe I block insures the incorporation of a high proportion oftrisubstituted double bonds, even in the presence of polar compoundssince myrcene contains a pendant trisubstituted double bond which is notinvolved in the polymerization process. In a coupling process similar tothat described above, block polymers containing polyisoprene end blocks(or any other polymerized monomer suitable for use in the I block)having a high 3,4-microstructure content can be obtained by adding thepolar compound prior to the isoprene (or another monomer)polymerization.

The use of the coupling technique for the production of triblockpolymers greatly reduces the reaction time necessary for the completionof polymerization, as compared to a sequential addition of isoprene,followed by butadiene, followed by isoprene. Such coupling techniquesare well known and utilize coupling agents, such as esters, CO₂, iodine,dihaloalkanes, silicon tetrachloride, divinyl benzene, alkyltrichlorosilanes and dialkyl dichlorosilanes. The use of tri- ortetra-functional coupling agents, such as alkyl trichlorosilanes orsilicon tetrachloride, permits the formation of macromolecules having 1-or 2- main chain branches, respectively. The addition of divinyl benzeneas a coupling agent has been documented to produce molecules having upto 20 or more separately joined segments.

The use of some of the coupling agents provides a convenient means ofproducing star-branched block and random polymers. The star-branchedblock polymers are made from any combination of blocks I and B, A and Dor I, D and A, discussed above, providing that each free end (i.e.,uncoupled end) of the star-branched polymer is either an I or an Ablock, respectively. The star-branched random polymers are made from anycombination of at least one diene of formula (1) and at least one dieneof formula (3), different from the diene of formula (1), or from atleast one aryl-substituted olefin, at least one diene of formula (1) andat least one diene of formula (3), different from the diene of formula(1). The molecular weight of the star-branched block and randomcopolymers will depend on the number of branches in each such copolymer,as will be apparent to those skilled in the art. Suitable couplingagents and reactions are disclosed in the following references which areincorporated herein by reference: U.S. Pat. Nos. 3,949,020; 3,594,452;3,598,887; 3,465,065; 3,078,254; 3,766,301; 3,632,682; 3,668,279; andGreat Britain patents 1,014,999; 1,074,276; 1,121,978.

The random copolymers of the invention are polymerized and/or coupled ina similar fashion, but all monomers, e.g., isoprene and butadiene, aremixed in a proper ratio prior to the reaction with the polarcompound-modified alkyl-lithium. In the random polymer preparation, ofcourse, only one stage is necessary.

Selective Hydrogenation

The selective hydrogenation reaction will also be described below usinga triblock of polyisoprene-polybutadiene-polyisoprene as an example.However, it will be apparent to those skilled in the art that anypolymers of this invention can be selectively hydrogenated in the samemanner.

The block copolymer is selectively hydrogenated to saturate the middle(polybutadiene) block of each of the triblocks. The method ofselectively hydrogenating the polybutadiene block is similar to that ofFalk, "Coordination Catalysts For The Selective Hydrogenation ofPolymeric Unsaturation", JOURNAL OF POLYMER SCIENCE: PART A-1, Volume 9,2617-2623 (1971), but it is conducted with the novel hydrogenationcatalyst and process used herein. Any other known selectivehydrogenation methods may also be used, as will be apparent to thoseskilled in the art, but it is preferred to use the method describedherein. In summary, the selective hydrogenation method preferably usedherein comprises contacting the previously-prepared block copolymer withhydrogen in the presence of the novel catalyst composition.

The novel hydrogenation catalyst composition and hydrogenation processare described in detail in previously cited U.S. application Ser. No.07/466,136. The hydrogenation catalyst composition is synthesized fromat least one transition metal compound and an organometallic reducingagent.

Suitable transition metal compounds are compounds of metals of GroupIVb, Vb, VIb, or VIII, preferably IVb or VIII of the Periodic Table ofthe Elements, published in LANGE's HANDBOOK OF CHEMISTRY (13th Edition,1985, McGraw-Hill Book Company, New York, John A. Dean, Editor).Non-limiting examples of such compounds are metal halides, e.g.,titanium tetrachloride, vanadium tetrachloride; vanadium oxytrichloride,titanium and vanadium alkoxides, wherein the alkoxide moiety has abranched or unbranched alkyl radical of 1 to about 20 carbon atoms,preferably 1 to about 6 carbon atoms. Preferred transition metalcompounds are metal carboxylates or alkoxides of Group IVb or VIII ofthe Periodic Table of the Elements, such as nickel (II)2-ethylhexanoate, titanium isopropoxide, cobalt (II) octoate, nickel(II) phenoxide and ferric acetylacetonate.

The organometallic reducing agent is any one or a combination of any ofthe materials commonly employed to activate Ziegler-Natta olefinpolymerization catalyst components containing at least one compound ofthe elements of Groups Ia, IIa, IIb, IIIa, or IVa of the Periodic Tableof the Elements. Examples of such reducing agents are metal alkyls,metal hydrides, alkyl metal hydrides, alkyl metal halides, and alkylmetal alkoxides, such as alkyllithium compounds, dialkylzinc compounds,trialkylboron compounds, trialkylaluminum compounds, alkylaluminumhalides and hydrides, and tetraalkylgermanium compounds. Mixtures of thereducing agents may also be employed. Specific examples of usefulreducing agents include n-butyllithium, diethylzinc, di-n-propylzinc,triethylboron, diethylaluminumethoxide, triethylaluminum,trimethylaluminum, triisobutylaluminum, tri-n-hexylaluminum,ethylaluminum dichloride, dibromide, and dihydride, isobutyl aluminumdichloride, dibromide, and dihydride, diethylaluminum chloride, bromide,and hydride, di-n-propylaluminum chloride, bromide, and hydride,diisobutylaluminum chloride, bromide and hydride, tetramethylgermanium,and tetraethylgermanium. Organometallic reducing agents which arepreferred are Group IIIa metal alkyls and dialkyl metal halides having 1to about 20 carbon atoms per alkyl radical. More preferably, thereducing agent is a trialkylaluminum compound having 1 to about 6 carbonatoms per alkyl radical. Other reducing agents which can be used hereinare disclosed in Stevens et al, U.S. Pat. No. 3,787,384, column 4, line45 to column 5, line 12 and in Strobel et al, U.S. Pat. No. 4,148,754,column 4, line 56 to column 5, line 59, the entire contents of both ofwhich are incorporated herein by reference. Particularly preferredreducing agents are metal alkyl or hydride derivatives of a metalselected from Groups Ia, IIa and IIIa of the Periodic Table of theElements, such as n-butyl lithium, sec-butyl lithium, n-hexyl lithium,phenyl-lithium, triethylaluminum, tri-isobutyl-aluminum,trimethylaluminum, diethylaluminum hydride and dibutylmagnesium.

The molar ratio of the metal derived from the reducing agent to themetal derived from the transition metal compound will vary for theselected combinations of the reducing agent and the transition metalcompound, but in general it is about 1:1 to about 12:1, preferably about1.5:1 to about 8:1, more preferably about 2:1 to about 7:1 and mostpreferably about 2.5:1 to about 6:1. It will be apparent to thoseskilled in the art that the optimal ratios will vary depending upon thetransition metal and the organometallic agent used, e.g., for thetrialkylaluminum/nickel(II) systems the preferred aluminum: nickel molarratio is about 2.5:1 to about 4:1, for the trialkylaluminum/cobalt(II)systems the preferred aluminum: cobalt molar ratio is about 3:1 to about4:1 and for the trialkylaluminum/titanium(IV) alkoxides systems, thepreferred aluminum: titanium molar ratio is about 3:1 to about 6:1.

The mode of addition and the ratio of the reducing agent to thetransition metal compound are important in the production of the novelhydrogenation catalyst having superior selectivity, efficiency andstability, as compared to prior art catalytic systems. During thesynthesis of the hydrogenation catalysts it is preferred to maintain themolar ratio of the reactants used to synthesize the catalystsubstantially constant. This can be done either by the addition of thereducing agent as rapidly as possible to a solution of the transitionmetal compound, or by a substantially simultaneous addition of theseparate streams of the reducing agent and the transition metal compoundto a catalyst synthesis vessel in such a manner that the selected molarratios of the metal of the reducing agent to the metal of the transitionmetal compound are maintained substantially constant throughoutsubstantially the entire time of addition of the two compounds. The timerequired for the addition must be such that excessive pressure and heatbuild-up are avoided, i.e., the temperature should not exceed about 80°C. and the pressure should not exceed the safe pressure limit of thecatalyst synthesis vessel.

In a preferred embodiment, the reducing agent and the transition metalcompound are added substantially simultaneously to the catalystsynthesis vessel in such a manner that the selected molar ratio of thereducing agent to the transition metal compound is maintainedsubstantially constant during substantially the entire time of theaddition of the two compounds. This preferred embodiment permits thecontrol of the exothermic reaction so that the heat build-up is notexcessive, and the rate of gas production during the catalyst synthesisis also not excessive-accordingly the gas build-up is relatively slow.In this embodiment, carried out with or without solvent diluent, therate of addition of the catalyst components is adjusted to maintain thesynthesis reaction temperature at or below about 80° C., which promotesthe formation of the selective hydrogenation catalyst. Furthermore, theselected molar ratios of the metal of the reducing agent to the metal ofthe transition metal compound are maintained substantially constantthroughout the entire duration of the catalyst preparation when thesimultaneous mixing technique of this embodiment is employed.

In another embodiment, the catalyst is formed by the addition of thereducing agent to the transition metal compound. In this embodiment, thetiming and the order of addition of the two reactants is important toobtain the hydrogenation catalyst having superior selectivity,efficiency and stability. Thus, in this embodiment, it is important toadd the reducing agent to the transition metal compound in that order inas short a time period as practically possible. In this embodiment, thetime allotted for the addition of the reducing agent to the transitionmetal compound is critical for the production of the catalyst. The term"as short a time period as practically possible" means that the time ofaddition is as rapid as possible, such that the reaction temperature isnot higher than about 80° C. and the reaction pressure does not exceedthe safe pressure limit of the catalyst synthesis vessel. As will beapparent to those skilled in the art, that time will vary for eachsynthesis and will depend on such factors as the types of the reducingagents, the transition metal compounds and the solvents used in thesynthesis, as well as the relative amounts thereof, and the type of thecatalyst synthesis vessel used. For purposes of illustration, a solutionof about 15 ml of triethylaluminum in hexane should be added to asolution of nickel(II) octoate in mineral spirits in about 10-30seconds. Generally, the addition of the reducing agent to the transitionmetal compound should be carried out in about 5 seconds (sec) to about 5minutes, depending on the quantities of the reagents used. If the timeperiod during which the reducing agent is added to the transition metalcompound is prolonged, e.g., more than 15 minutes, the synthesizedcatalyst is less selective, less stable and may be heterogeneous.

In the embodiment wherein the reducing agent is added as rapidly aspossible to the transition metal compound, it is also important to addthe reducing agent to the transition metal compound in theaforementioned sequence to obtain the novel catalyst. The reversal ofthe addition sequence, i.e., the addition of the transition metalcompound to the reducing agent, or the respective solutions thereof, isdetrimental to the stability, selectivity, activity and homogeneity ofthe catalyst and is therefore undesirable.

In all embodiments of the hydrogenation catalyst synthesis, it ispreferred to use solutions of the reducing agent and the transitionmetal compound in suitable solvents, such as hydrocarbon solvents, e.g.,cyclohexane, hexane, pentane, heptane, benzene, tolune or mineral oils.The solvents used to prepare the solutions of the reducing agent and ofthe transition metal compound may be the same or different, but if theyare different, they must be compatible with each other so that thesolutions of the reducing agent and the transition metal compound arefully soluble in each other.

The hydrogenation process comprises contacting the unsaturated polymerto be hydrogenated with an amount of the catalyst solution containingabout 0.1 to about 0.5, preferably about 0.2 to about 0.3 mole percentof the transition metal based on moles of the polymer unsaturation. Thehydrogen partial pressure is about 5 psi to about several hundred psi,but preferably it is about 10 to about 100 psi. The temperature of thehydrogenation reaction mixture is about 25° to about 80° C., sincehigher temperatures may lead to catalyst deactivation. The length of thehydrogenation reaction may be as short as 30 minutes and, as will beapparent to those skilled in the art, depends to a great extent on theactual reaction conditions employed. The hydrogenation process may bemonitored by any conventional means, e.g., infra-red spectroscopy,hydrogen flow rate, total hydrogen consumption, or any combinationthereof.

After the hydrogenation reaction is completed, the hydrogenationcatalyst must be removed from the polymer by any conventional means, forexample, in the case of a nickel-based catalyst by contacting thepolymer with a complexing agent, such as a high molecular weight diamine(e.g., Jeffamine D-2000 from Texaco), and then with an acid, e.g.,sulfuric, phosphoric or hydrochloric acid, in the presence of anoxidizing agent, e.g., air or hydrogen peroxide. The polymer solution isthen water-washed and the polymer isolated by conventional methods,e.g., steam or alcohol flocculation or solvent evaporation.

Crosslinking And Functionalization Of The Terminal Blocks

In addition to acting as sites for vulcanization, the unsaturatedterminal blocks of the block polymers of this invention can bechemically modified to provide benefits obtained with similarmodifications of existing commercial materials, such as butyl rubber orEPDM. In some instances, the benefits obtained by a chemicalmodification of butyl rubber or EPDM may be magnified using theelastomers of our invention as a matrix instead of the butyl rubber orEPDM because of their intrinsically superior elastomeric properties.

An example of such a chemical modification of the polymers of thisinvention is sulfonation of the olefinic unsaturation of the I blocks orpolymerized dienes of formula (1) of any polymers of this inventioncontaining the I blocks or polymerized dienes of formula (1), followedby neutralization of the thus-formed polymeric sulfonic acid with metalions or amines. When such a modification is performed on a commercialethylene-propylene-diene monomer (EPDM) rubber, a thermoplasticelastomer which behaves like a vulcanized rubber at room temperature butcan be shaped at higher temperatures is produced. A description of anexample of a process for and product description of such a chemicallymodified EPDM can be found in IONS IN POLYMERS, Advances in ChemistrySeries 187, American Chemical Society, Washington, D.C. 1980, pp. 3-53,incorporated herein by reference. Following the procedures used for EPDMdescribed in the aforementioned publication with the triblock of ourinvention, thermoplastic elastomers with greatly improved elongationproperties were prepared.

It is known that the halogenation of the unsaturation in butyl rubber(based upon isoprene monomer) prior to the vulcanization treatment,produces dramatic changes in vulcanization rate and provides greaterversatility in the choice of vulcanizing agents. Since the residualunsaturated groups in the first embodiment of our invention, present inthe I block, in the most preferred embodiment, may also be based onisoprene monomer, the halogenation of the polymer of this embodimentprovides the same benefits, but with the retention of the greaterelongation characteristics inherent in the invention polymer. The samebenefits will be obtained with any other dienes which can be used toprepare the block I of this embodiment of the invention, and thereforeany polymers of this invention containing any such dienes can behalogenated in the same manner as the butyl rubber. Any other polymersof this invention containing the polymerized dienes of formula (1) orblocks I can also be halogenated in the same manner.

It is also known that the reaction of EPDM with maleic anhydride atelevated temperatures (e.g., about 150° C. to about 250° C.) producesmaleic modified EPDM which is used commercially as an impact modifier,particularly for Nylon. Similar modification of the polymers of anyembodiments of our invention occurs readily, since the residual isopreneunsaturation, primarily of the illustrated 3,4-type, is known to be morereactive with maleic anhydride than are the internal bonds found inEPDM. The resultant impact modifier, because of its greater elongation,provides superior properties when blended with Nylon.

EPDM polymers which have been modified with polar functionality areutilized as dispersant type viscosity index improvers in multigradelubricants. A great number of patents are devoted to such modifications.Any of the modifications performed on EPDM for this purpose can beperformed with the polymers of this invention. Typical modificationswhich can be used with the polymers of this invention are described in:U.S. Pat. NOS. 3,099,644; 3,257,349; 3,448,174; 3,997,487; 3,870,841;3,642,728; 3,847,854; 3,437,556; 4,557,849; 4,032,700; 3,899,434;4,557,847; 4,161,452; 4,170,562; 4,517,104; 4,320,017; 4,502,972;4,098,710; 4,007,121; 4,011,380; 4,033,888; 4,145,298; 4,402,844;4,146,489 and British patent 1,072,796, the disclosures of all of whichare incorporated herein by reference.

The above examples illustrate only some of the potentially valuablechemical modifications of the polymers of this invention. The highmolecular weight block polymers of this invention, providing a means fora wide variety of chemical modifications only at the ends of themolecule (i.e., at the I blocks only), present the opportunity toprepare materials previously impossible because of the lack ofavailability of such polymers. Some examples of well known chemicalreactions which can be performed on polymers of this invention are foundin E. M. FETTES, CHEMICAL REACTIONS OF POLYMERS, High Polymers, Vol. 19,John Wiley, New York, 1964, incorporated herein by reference.

Until the instant invention, it has not been possible to producehydrocarbon elastomers having very large distance between crosslinks(high M_(c)) after vulcanization. Our invention provides blockhydrocarbon polymers capable of being vulcanized to a perfect networkwith a distance between crosslinks substantially equivalent to thedimensions of the unvulcanized elastomeric molecule. In addition to theexpected improvements in elastomeric properties, the saturated mainchain of the polymers of our invention provides a high degree ofoxidative and thermal stability. Unique materials can also be obtainedby chemical modifications of the block polymers of this invention, sincesuch modifications can be carried out selectively only at theunsaturated terminal ends of the molecules.

The crosslinking of the selectively hydrogenated block polymers of thisinvention is conducted in a conventional manner by contacting the blockcopolymer with a suitable crosslinking agent or a combination of suchagents. The crosslinking process produces a copolymer having uniformdistance between cross-links.

The block copolymers can also be functionalized by reacting the terminalblocks containing unsaturated groups with various reagents to producefunctional groups, such as hydroxyl, epoxy, sulfonic acid, mercapto,acrylate or carboxyl groups. Functionalization methods are well known inthe art.

The random copolymers may also be cross-linked or functionalized in thesame manner as the block copolymers.

The block and random copolymers, including the star-branched polymers,of this invention can be used in a variety of applications, e.g., toproduce electrical insulation, pressure sensitive adhesives, sealants,rubberized asphalts, in automotive applications, e.g., hoses, tubing,weatherstripping, in construction industry, e.g., to produce gaskets,rubber sheeting for roofing, pond and ditch liners, and in many otherapplications.

The following Examples further illustrate additional features of theinvention. However, it will be apparent to those skilled in the art thatthe specific reactants and reaction conditions used in the Examples donot limit the scope of the invention.

In all of the following examples, the experimental work was performedwith dried reactors and equipment and under strictly anaerobicconditions. Extreme care must be used to exclude air, moisture and otherimpurities capable of interfering with the delicate chemical balanceinvolved in the synthesis of the polymers of this invention, as will beapparent to those skilled in the art.

EXAMPLE 1 (Isoprene-Butadiene-Isoprene Triblock Polymer)

Two hundred milliliters (ml) of purified dried cyclohexane (99.5%available from Phillips Petroleum Co.) were introduced under nitrogenatmosphere into a two quart glass bowled stirred pressure reactor. Thereactor was equipped with an air driven stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with valve, a syringe injection port containing a vitronrubber gasket and a blow-out disk (200 psi). Three milliliters (ml) of a0.01M solution of dipyridyl indicator in cyclohexane and 6.5 ml (70millimoles-mm) of freshly distilled tetrahydrofuran were injected intothe reactor, whose contents were then heated to 54° C. The solution wastitrated by slow addition of 0.1 molar butyl lithium (BuLi) until a redcolor was observed indicating the deactivation of all impurities. Next,3.0 ml (2 g., 30 mm) of purified isoprene and 20 ml of 0.1 m BuLisolution were injected into the reactor. Oligomerization of the isopreneto form the initial block was completed in approximately one hour. Tothe solution of living polyisopreneyl anions was added an additional oneliter of pre-titrated cyclohexane. To form the second block 100 grams ofpurified butadiene were slowly pressurized into the reactor at a rate tomaintain temperature below 60° C. After an hour, the reactor pressurehad dropped to the initial value and the formation of theisoprene-butadiene block copolymer was complete. The diblock livinganion was coupled to a triblock having twice the molecular weight of thediblock by the introduction of 11 ml of a 0.1M phenyl benzoate solution(in cyclohexane). The mixture, which contained a 10% stoichiometricexcess of the coupling agent, was kept with stirring at 50° C. for anadditional thirty minutes and then pressurized from the reactor. Aportion of the unhydrogenated triblock polymer was isolated byflocculation in isopropanol containing an antioxidant Irganox 1076 toprevent the crosslinking of the highly unsaturated triblock. The solidpolymer sample was filtered and dried in a vacuum oven for 18 hours.Infrared (FTIR) analysis showed the butadiene microstructure to have 50%1,2- and 50% of 1,4-composition. Gel permeation chromotography of thesample, using differential refractive index and DAWN laserlight-scattering dual detectors, determined the number average molecularweight (Mn) and weight average molecular weight (Mw) of the polymer tobe 135,900 and 139,400, respectively, for a dispersity (Mw/Mn) of 1.08.

EXAMPLE 2 (Hydrogenation of Central Polybutadiene Block ofIsoprene-Butadiene-Isoprene Triblock)

This example illustrates the selective hydrogenation of the centralpolybutadiene block of an isoprene-butadiene-isoprene triblock polymer.

One hundred milliliter (ml) of cyclohexane containing 8 grams ofdissolved triblock polymer as prepared in Example 1 was introduced intoa PARR shaker hydrogenation apparatus. This amount of polymer represents0.142 moles of polybutadiene unsaturation. The hydrogenation catalystwas prepared by adding 10.8 ml of a nickel octoate solution (6% byweight nickel) to a solution of 45.2 millimoles of triethyl aluminum in102.2 ml of hexane. The nickel octoate was added slowly (over about 1hour) using a syringe pump to give a final catalyst solution which was0.1 molar in nickel and had an Al/Ni molar ratio of 3.6/1.0. The shakerapparatus was purged 4 times with hydrogen gas, sealed, heated andpressured to 50 psig with hydrogen. Temperature was maintained at 50° C.and the reaction vessel was shaken for four hours. Analysis of analiquot of the product by FTIR demonstrated complete loss of absorptionrelated to the 1,2-butadiene (910 and 994 cm⁻¹) and trans 1,4-butadiene(967 cm⁻¹), but retention of absorption related to 3,4-isoprene(vinylidene) structure (888 cm⁻¹). The reaction mixture was degassed andtreated with 3-4 drops of Jeffamine D-2000 (a polyether diamine) and 1ml of HCl (6N). After stirring for a short time, the dark catalyst colorhad discharged and the solution was added to 200 ml of isopropanolcontaining an antioxidant (0.5 g of Irganox 1076). The precipitatedpolymer was isolated and dried in a vacuum oven. Analysis of the polymerindicated essentially no residual nickel (less than 1 ppm).

EXAMPLE 3 Isoprene/Styrene-Butadiene-Isoprene/Styrene Triblock Polymer

This example illustrates the preparation of a triblock polymer whereinthe terminal blocks consist of isoprene-styrene copolymers.Incorporation of low levels of styrene into the end block is beneficialwith certain methods of vulcanizing the final selectively hydrogenatedtriblock.

520 grams of cyclohexane, 7.4 ml of tetrahydrofuran, 5 grams of isopreneand 5 grams of styrene were charged into a clear, dry one gallonautoclave kept under a 5 psig N₂ pressure. The contents were stirred(1500 rpm) and warmed to 55° C. Polymerization was initiated by theaddition of 3.6 ml of a 1.6N solution of n-butyl lithium. The reactionwas allowed to proceed for two hours (over 10 half times) at which time1536 g of cyclohexane (pre-titrated with BuLi to a dipyridyl end point)were added to the reactor. Butadiene (400 ml) was pumped as a liquidinto the reactor. Cooling water was employed as necessary to maintain55° C. Polymerization of the butadiene was complete in one hour. Theformed diblock was then coupled by the addition of 2.75 millimoles ofphenyl benzoate as a 0.1 molar solution in cyclohexane. After 0.5 hourreaction time the final polymer was pressured from the reactor. Totalsolids measurement confirmed 100% monomer conversion. A small sample wasisolated for analysis by precipitation in isopropanol. The vinyl (1,2-)content of the butadiene center block was shown to be 52% by FTIR. A GPCanalysis using the Dawn detector showed:

    ______________________________________                                                   M.sub.n                                                                            = 93,470                                                                 M.sub.w                                                                            = 96,210                                                                 M.sub.w                                                                            = 1.03                                                                   M.sub.n                                                            ______________________________________                                    

The magnitude of the molecular weight and narrowness of the molecularweight distribution confirm the success of the coupling reaction.

EXAMPLE 4 Hydrogenation of Example 3 Triblock Polymer

This example demonstrates the hydrogenation of the triblock polymerprepared substantially in the manner of Example 3, utilizing a catalystprepared in a different manner than that described in Example 2.

A 400 ml pressure bottle containing a magnetic stir bar was capped witha rubber liner and two-holed bottle cap. To the bottle was added 160 mlof cyclohexane and 21.6 ml of nickel octoate solution (6% nickel) togive 22.5 millimoles of nickel as a 0.124 molar solution. One hole ofthe bottle cap was pierced with a 50 ml syringe, with syringe lock,containing 46.4 ml of 1.73 molar triethyl aluminum (80.27 millimoles).The other hole was pierced with a flexible neddle cannula whose otherend was submersed in mineral oil. While the contents of the bottle werestirred, the triethylaluminum solution was added as rapidly as possiblewithout allowing the contents of the bottle to boil. The resultanthomogenous dark solution was 0.1 molar in nickel and 0.36 molar inaluminum. This order of addition is the reverse of that reported by Falkand, in addition to being less time consuming, appears to give acatalyst with superior reproduceability and lifetime.

Into a one gallon autoclave was charged 155 grams of the triblockpolymer prepared substantially in the manner of Example 3 as a 7.5 wt.percent solution in cyclohexane. This amount of polymer contained 2.75moles of unsaturation from the polybutadiene segment. Ethoxy acetic acid(3.1 ml of 0.1M) was added and stirred at 1500 rpm for 0.5 hours tocomplete the complex with the Li cation. To this solution was added 70ml of the catalyst solution prepared above. The reactor was spargedseveral times with hydrogen and then pressured to 70 pounds withhydrogen and warmed to 55° C. Several other catalyst additions,totalling 60 more ml, followed. After 4 hours, only the vinylidene(3,4-microstructure) unsaturation was observeable by FTIR. Afterhydrogenation, the polymer solution was shortstopped and the polymer wasisolated as described in Example 2. The polymer contained less than 1ppm of residual nickel; its M_(n) was 118,500, the M_(w) was 129,000 andthe M_(w) /M_(n) =1.09.

The M_(n) of the starting polymer was 110,000, its M_(w) was 112,900,with M_(w) /W_(n) =1.03.

Thermogravimetric analysis (TGA) of a sample of this hydrogenatedpolymer in nitrogen showed that only 10% of the polymer weight was lostat 435° C. and that TGA in oxygen resulted in a 10% weight loss at 360°C. (10 degree temperature rise per minute). The T_(g) of the elastomerwas -60° C.

These results illustrate the execellent thermal and oxidative stabilityof the polymers of this invention.

EXAMPLE 5 Comparison of Example 4 Polymer With Commercial EPDM Rubbers

This example compares properties of the triblock polymer of Example 4and two commercial EPDM rubbers with and without calcium carbonatefiller (Multiflex MM).

The curatives (vulcanizing agents) used are known to those skilled inthe art and are identified in the previously-cited references. Theingredients listed below were mixed in a Brabender extruder at 50 rpmallowing the temperature to rise to about 100° C. The samples were curedin a Carver press for one hour at 160° C. under 6000 psi pressure andallowed to stand at least 24 hours at room temperature prior to testing.The results reported below are, in each case, the average obtained fromtwo separate but identical mixes.

                  TABLE 1                                                         ______________________________________                                                       RUN                                                            Ingredients      A      B      C    D     E                                   ______________________________________                                        MIX RECIPE                                                                    ELASTOMER OF     100    --     --   100   --                                  EXAMPLE 4 (parts)                                                             ROYALENE 501.sup.X (parts)                                                                     --     100    --   --    100                                 NORDEL 1470.sup.Y (parts)                                                                      --     --     100  --    --                                  MULTIFEX MM.sup.Z (parts/100                                                                   --     --     --   100   100                                 parts of rubber-phr)                                                          TMTD.sup.i (phr)  2      2      2    2     2                                  DTDM.sup.ii (phr)                                                                              1.5    1.5    1.5  1.5   1.5                                 ZDBDC.sup.iii (phr)                                                                            1.5    1.5    1.5  1.5   1.5                                 ZDMDC.sup.iv (phr)                                                                             1.5    1.5    1.5  1.5   1.5                                 SULFUR (phr)     0.4    0.4    0.4  0.4   0.4                                 ZnO (phr)        2.5    2.5    2.5  2.5   2.5                                 STEARIC ACID (phr)                                                                             1.5    1.5    1.5  1.5   1.5                                 PHYSICAL PROPERTIES                                                           % Gel.sup.W      89.3   88.6   88.4 --    --                                  TENSILE          264    284    346  1210  782                                 STRENGTH (PSI)                                                                ELONGATION (%)   738    410    435  1797  671                                 ______________________________________                                         .sup.W Soxhlet Extraction By Boiling Hexane; 24 hrs; 1 gram sample            .sup.X From Uniroyal Chemical Co.                                             .sup.Y From E.I. DuPont & de Nemours and Co.                                  .sup.Z Untreated Calcium Carbonate (From Pfizer)                              .sup.i = TETRAMETHYL THIURAM DISULFIDE                                        .sup.ii = DITHIODIMORPHOLINE                                                  .sup.iii = ZINC DIBUTYL DITHIOCARBAMATE                                       .sup.iv = ZINC DIMETHYL DITHIOCARBAMATE                                  

The superior elongation of the elastomers of our invention is clearlyevident in the filled and unfilled mixes. The high elongation is not theresult of undervulcanization, as shown by the low level of extractiblesin the gel determination.

EXAMPLE 6 Sequential Polymerization of Triblock Copolymer

This example illustrates the preparation of triblock polymer essentiallyidentical to that described in Examples 3 and 4, but synthesized viasequential polymerization.

The apparatus utilized was the same as that described in Example 1. Inthis Example, which does not require a coupling step as earlierdescribed, the three blocks of the polymer chain are polymerizedsequentially to produce a polymer of 100,000 Mn directly. While catalystusage is decreased in this method, the time necessary for completion ofthe polymerization reaction is greatly increased. It is not, therefore,the preferred technique for the production of symmetrical triblocks butdoes have the advantage of permitting the presence of two dissimilar endblocks, if desired.

To form the initial block, the procedures of Example 1 were followed,except that one gram of isoprene and one gram of styrene werepolymerized using 1.0 millimoles of BuLi. After addition of the solventas in Example 1, 96 grams of butadiene were added to the reactor andallowed to polymerize for one hour. One gram each of isoprene andstyrene were added and the polymerization was allowed to proceed for 15hours. This lengthly reaction time is necessary and reflects the lowconcentration of catalyst and monomer necessitated by the conditions inthis block sequential polymerization.

Work up and hydrogenation of the polymer as in Examples 1-4 produced aselectively hydrogenated triblock having M_(n) =104,200 and M_(w)=112,540.

EXAMPLE 7 High Styrene Content Triblock Copolymer

This example describes the preparation of a polymer similar to that ofExample 3, but having considerably higher styrene content.

To the apparatus described in Example 1 was charged 1100 mi ofcyclohexane, 3 ml of 0.01 m dipyridyl, 6.5 mi of tetrahydrofuran (THF),33 mi (30 g) of styrene and 3 ml (2 g) of isoprene.

The solution was warmed to 55° C. and titrated with BuLi, and after theend point, 20 ml of 0.1 molar BuLi were added. After 2 hours, 70.3 gramsof purified butadiene were added. The butadiene was allowed topolymerize for an hour and 11 ml of a 0.1M phenyl benzoate solution wereadded to couple the diblock. The polymer work up and hydrogenation wasas previously described. The polymeric product displayed unsaturation byFTIR corresponding to vinylidene (3,4-isoprene) double bonds only. Theresultant material displayed thermoplastic elastomer properties similarto polymers made without the low level of isoprene used in this example.The polymer of the example can, however, be chemically vulcanized by anynormal method. Thus, the polymer of this example is both a thermoplasticelastomer when uncured and a thermoset elastomer if cured. Thisinvention provides the user with a choice not available in heretoforeexisting commercial hydrocarbon elastomers and also provides anelastomer whose excellent physical properties provided by the styreneend blocks of current thermoplastic elastomers can be retained atgreatly elevated temperatures (100°-150° C.).

EXAMPLE 8 Thermoplastic Ionic Elastomer

In this example, the preparation of a thermoplastic ionic elastomerutilizing a selectively hydrogenated triblock polymer as a substrate isdescribed.

Fifty grams of triblock polymer (M_(n) =111,820) similar to thosedescribed in Examples 1 and 2 were dissolved in 1 liter of cyclohexane.Acetyl sulfate was prepared by mixing 2.7 ml of acetic anhydride (28.6mm) with 1 ml (18 mm) of concentrated sulfuric acid at 0° C. The formedacetyl sulfate was added dropwise with stirring to the rubber solution.After stirring at room temperature for 1/2 hour, the resultant productwas divided into two equal portions.

To one portion (A) was added 1.85 grams of sodium acetate as a solutionin methanol and water. Next, there was added 0.25 grams of Irganox 1076axtioxidant and 12.0 grams of zinc stearate as an inolyzer. After briefstirring, the mixture was added to one liter of isopropanol toprecipitate the polymer. The flocculated polymer was isolated and driedin a vacuum oven to constant weight.

The second portion (B) was treated similarly except that 4.9 grams ofzinc acetate were substituted for the sodium acetate.

Both portions, (A) and (B), were individually homogenized by mixing themin a Brabender mixer. The samples were then pressed in a mold at 160° C.for 30 minutes at 6000 pounds pressure to give molded squaresapproximately of 70 mils thickness. The stress-strain properties ofdumbells cut from the molded squares were then measured.

    ______________________________________                                                      Samples                                                                       A        B                                                      ______________________________________                                        Cations         Na.sup.+  + Zn.sup.+2                                                                    Zn.sup.+2                                          Tensile, psig   1459       3055                                               Elongation, %   1359       1736                                               ______________________________________                                    

The samples, with their widely spaced ionic domains, molded smoothly andeasily. The measured elongations are far above those reported for EPDMtreated in a similar manner to our polymer of the portion B where atensile strength of 3040 psig and an elongation of only 460% wereobserved (e.g., IONS IN POLYMERS, Adi Eisenberg, Editor, Advances inChemistry Series, 187 American Chemical Society, Washington, D.C. 1980,p. 42).

It will be apparent to those skilled in the art that the specificembodiments discussed above can be successfully repeated withingredients equivalent to those generically or specifically set forthabove and under variable process conditions.

From the foregoing specification, one skilled in the art can readilyascertain the essential features of this invention and without departingfrom the spirit and scope thereof can adapt it to various diverseapplications.

We claim:
 1. A solid, star-branched random copolymer comprising at leastone polymerized conjugated diene having at least five (5) carbon atomsand the following formula ##STR13## wherein R¹ -R⁶ are each hydrogen ora hydrocarbyl group, provided that at least one of R¹ -R⁶ is ahydrocarbyl group and provided that the structure of the residual doublebond in the polymerized diene of formula (1) has the following formula##STR14## wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen ora hydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups,and at least one polymerized conjugated diene, different from the dieneof formula (1), having at least four (4) carbon atoms and the followingformula ##STR15## wherein R⁷ -R¹² are each hydrogen or a hydrocarbylgroup, provided that the structure of the residual double bond in thepolymerized diene of formula (3) has the following formula ##STR16##wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(a) or R^(b) is hydrogen, oneof R^(c) or R^(d) is hydrogen, and at least one of R^(a), R^(b), R^(c)or R^(d) is a hydrocarbyl group, wherein the copolymer comprises about1.0 to about 25% by mole of the polymerized conjugated diene of formula(1), and about 75 to about 99% by mole of the polymerized conjugateddiene of formula (3), said copolymer being selectively hydrogenated sothat the polymerized conjugated diene of formula (3) is substantiallycompletely hydrogenated and thereby contains substantially none of theoriginal unsaturation and the polymerized conjugated diene of formula(1) retains a sufficient amount of its original unsaturation tovulcanize said copolymer.
 2. A sulfonated polymer produced by a methodcomprising sulfonating the polymer of claim 1, followed byneutralization of the thus-formed polymeric sulfonic acid with metalions or amines.
 3. A maleated polymer produced by a method comprisingcontacting the polymer of claim 1 with maleic anhydride.
 4. Ahalogenated polymer produced by a method comprising halogenating thepolymer of claim
 1. 5. A solid, star-branched random copolymercomprising about 0.3 to about 15% by mole of at least one polymerizedaryl-substituted olefin, about 1.0 to about 25% by mole of at least onepolymerized conjugated diene having at least five (5) carbon atoms andthe following formula ##STR17## wherein R¹ -R⁶ are each hydrogen or ahydrocarbyl group, provided that at least one of R¹ -R⁶ is a hydrocarbylgroup and provided that the structure of the residual double bond in thepolymerized block I has the following formula ##STR18## wherein R^(I),R^(II), R^(III) and R^(IV) are each hydrogen or a hydrocarbyl group,provided that either both R^(I) and R^(II) are hydrocarbyl groups orboth R^(III) and R^(IV) are hydrocarbyl groups, and the remainder apolymer of at least one conjugated diene, different from the diene offormula (1), having at least four (4) carbon atoms and the followingformula ##STR19## wherein R⁷ -R¹² are each hydrogen or a hydrocarbylgroup, provided that the structure of the residual double bond in thepolymerized diene of formula (3) has the following formula ##STR20##wherein R^(a), R^(b), R^(c) and R^(d) are each hydrogen (H) or ahydrocarbyl group, provided that one of R^(a) or R^(b) is hydrogen, oneof R^(c) or R^(d) is hydrogen and at least one of R^(a), R^(b), R^(c)and R^(d) is a hydrocarbyl group.
 6. The copolymer of claim 5 which isselectively hydrogenated so that the polymerized conjugated diene offormula (3) is substantially completely hydrogenated and therebycontains substantially none of its original unsaturation, while thepolymerized conjugated diene of formula (1) retains a sufficient amountof its original unsaturation to vulcanize said copolymer.
 7. Asulfonated polymer produced by a method comprising sulfonating thepolymer of claim 6, followed by neutralization of the thus-formedpolymeric sulfonic acid with metal ions or amines.
 8. A maleated polymerproduced by a method comprising contacting the polymer of claim 6 withmaleic anhydride.
 9. A halogenated polymer produced by a methodcomprising halogenating the polymer of claim
 6. 10. A solidstar-branched random copolymer wherein each random copolymer branchcomprises either 1) about 1.0 to 25 mol % of at least one polymerizedhydrocarbon conjugate diene (I) monomer containing at least five (5)carbon atoms, with at least one carbon atom of each pair of residualdouble-bonded carbon atoms of polymerized conjugated diene (I) unitsbeing additionally single-bonded to two carbon atoms, and about 75 to 99mol % of at least one polymerized hydrocarbon conjugated diene (B),which is different from conjugated diene (I) and contains at least four(4) carbon atoms, with each residual double-bonded carbon atom ofpolymerized conjugated diene (B) units being additionally bonded to ahydrogen atom; or 2) about 0.3 to 15 mol % of at least one polymerizedaryl-substituted olefin, about 1.0 to 25 mol % of said polymerizedconjugated diene (I), and the remainder said polymerized conjugateddiene (B), said star-branched random copolymer being selectivelyhydrogenated so that said polymerized conjugated diene (B) units aresubstantially completely hydrogenated and contain substantially none ofthe original unsaturation, while said polymerized conjugated diene (I)units retain sufficient amount of their original unsaturation tovulcanize said copolymer.
 11. The copolymer of claim 10 wherein, afterthe hydrogenation reaction, the Iodine Number of said polymerizedconjugated diene (I) units is about 10 to about 100% of the IodineNumber prior to the hydrogenation reaction.
 12. The copolymer of claim11 wherein, after the hydrogenation reaction, the Iodine Number of saidpolymerized conjugated diene (I) units is about 25 to about 100% of theIodine Number prior to the hydrogenation reaction.
 13. The copolymer ofclaim 12 wherein, after the hydrogenation reaction, the Iodine Number ofsaid polymerized conjugated diene (I) units is about 50 to about 100% ofthe Iodine Number prior to the hydrogenation reaction.
 14. The copolymerof claim 13 wherein, after the hydrogenation reaction, the Iodine Numberof said polymerized conjugated diene (B) units is about 0 to about 10%of the Iodine Number prior to the hydrogenation reaction.
 15. Thecopolymer of claim 10 wherein diene (I) is isoprene,2,3-dimethyl-butadiene, myrcene, 2-methyl-1,3-pentadiene,3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene,3-phenyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene,2-benzyl-1,3-butadiene, 2-p-tolyl-1, 3-butadiene or mixtures thereof.16. The copolymer of claim 15 wherein diene (I) is isoprene, myrcene or2-methyl-1,3-pentadiene.
 17. The copolymer of claim 16 wherein diene (I)is isoprene.
 18. The copolymer of claim 10 wherein diene (B) is1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene,1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octoadiene,3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene,1,3-decadiene, 2,4-decadiene, 3,5-decadiene or mixtures thereof.
 19. Thecopolymer of claim 18 wherein diene (B) is 1,3-butadiene,1,3-pentadiene, 2,4-hexadiene or 1,3-hexadiene.
 20. The copolymer ofclaim 19 wherein diene (B) is 1,3-butadiene.
 21. The copolymer of claim10 which is a category 2) copolymer wherein said aryl-substituted olefinis styrene, alpha-methyl styrene, or 1,1-diphenylethylene.
 22. Thecopolymer of claim 21 wherein said aryl-substituted olefin is styrene.